ADDENDUM, 8 months after initial purchase. Not sure I can recommend this as highly as before. I still use two of these on a daily basis, to create the 3-screen display described below. But I've noticed that the screens will sometimes give a big blink, go black for a few seconds and when they recover, several things will go haywire: Resolution becomes wrong, portrait/landscape setting is wrong, and the desktop icons will resort themeselves into nonsensical locations. Usually I can just restart the computer and everything will recover, but not always. I think it's a hardware/software conflict - I believe the Nvidia video controller built into my motherboard is trying to get control of the USB displays, and this seems to mess things up. You may not have the same issue. The restart-fixable fault occurs about every 8 days, whereas the major fault where everything gets fouled up occurs about every 2 months. And one other fault - sometimes one of the screens will suddenly begin to display a series of primary colors, blinking red-green-blue forever until I turn that monitor off and on again. By the way, I do have the latest video drivers loaded for all devices.
ORIGINAL REVIEW: A little background and history: My stock trading multi-monitor setup has 3 monitors: the center 24" widescreen monitor is 1920x1200, and the secondary monitors on either side are 19" widescreens (1440x900). One of the side monitors is rotated +90 degrees and the other rotated -90 degrees to portrait mode. My desktop PC had a built-in video driver. In my first attempt to build a triple monitor system, I naively installed a dual output ATI video card, thinking I could use those two outputs in conjunction with my existing internal video to acheive a triple monitor output. I was disappointed to discover that the ATI card disabled the internal video card, so I was left with a dual monitor system. I lived with that for a while, but found that the ATI card frequently "forgot" which monitor was the primary monitor, "forgot" that one monitor was rotated to portrait mode, and even "forgot" that there were two monitors. I would turn on the PC to discover that the primary monitor display was rotated 90 degrees and the secondary monitor had no display, so I would have to tilt my head sideways while I tried to reset all the parameters to my preferred settings. The saved settings file seemed very unreliable.
Still wanting 3 displays, I finally ponied up almost $800 for a Matrox quad monitor display card. What a disaster. The available resolution settings did not accomodate widescreens, and certainly did not accomodate having one or more screens rotated. Each pair of the four outputs had to be the same resolution, and you could not control placement of the primary screen between the secondary screens, in terms of the mouse movement.
As I continued to research multi-monitor displays, I finally discovered USB multimonitor display adaptors. I purchased the Diamond BVU195 rather than some less expensive alternatives for several reasons: It supported a higher resolution than many other products, and it offered Vista compatibility. (The cheaper Diamond BVU160 is identical in every specification except is not certified for Vista and Windows 7. I do wonder if this is an artificial price difference. If anybody has successfully installed the BVU160 on a Vista system, I'd like to hear about it. The BVU195 Vista driver is available as a free download from the Diamond website, and I have a suspicion that you may be able to purchase the cheaper BVU160 hardware and download the BVU195 Vista driver for it. However, I HAVE NOT TESTED THIS, so it's buyer beware if you attempt this.)
Anyway, I bought two of the BVU195 and installed them in my desktop, to drive the smaller secondary displays that sit right and left of my primary display. My primary display is driven by the video built into my desktop, while the secondary displays are driven by the two BVU195 plugged into two USB ports. Installation and setup was far easier and faster than with the earlier ATI and Matrox experiments. The BVU195 coexists perfectly with the pre-existing on-board video driver. I was very pleased to discover that I can independantly and easily control the resolution, rotation, and placement of each secondary monitor in relation to the primary monitor. If I want, I can place the secondary monitors above or below the primary monitor, or both on one side, and the mouse arrow will flow from one screen to the next in the expected fashion.
I was so pleased by the experience that I gave a presentation on this setup to my local stock trading Meetup group. I was able to easily demonstrate setting up the multi-monitor display on a PC desktop, a PC laptop, and a Macintosh laptop. At one point of the presentation, I was driving a 46" LCD TV at 1900x1080p, a 24" monitor at 1920x1200, and a 19" monitor in portrait mode at 900x1440. Since then, two other traders in the group have purchased the BVU195 for use in a dual monitor PC system and a MacIntosh triple monitor system. Neither of those traders is "computer savvy," but they had no problems installing and configuring the BVU195.
The BVU195 video driver operates under the DisplayLink specification, which allows a maximum of 6 USB video drivers to be attached to your system. If your existing system has a single output video card built in, then the maximum total number of displays is 7. Most laptops have a built-in dual video driver, so with a laptop you will probably have a maximum of 8 displays possible. However, driving that many displays with a laptop, I'd recommend a USB expansion hub with independant power supply to drive that many BVU195s. I haven't tested the BVU195 when driven through a USB expansion hub, but I'd anticipate no problem.
I'm very pleased that I can easily expand the system to more and more monitors over time.
One limitation of any USB video driver is the speed and graphics processing power is not suitable for high-end gaming. USB video drivers such as the BVU195 do not contain an independant graphics processor nor an independant graphics memory cache. Therefore, it does not do a good job rendering textures and rapid movement in some video games. It's also not recommended for watching movies from DVD, particularly Blu-Ray.
My only negative comment about the BVU195: I've noticed that about every 30 to 45 minutes, the screens driven by the BVU195 will momentarily go blank for about 1 second. My two stock trading friends with the same device are reporting the same behavior on PCs and MacIntosh. In my house, I've had the BVU195 plugged into 3 different computers, one of which is XP based while the other two are Vista, and I see the same occasional blinking on all monitors driven by the BVU195, regardless of the computer or operating system, so I would assume this behavior is common to all installations. It's not an important negative issue for me, but I see other reviewers have reported the same behavior, so you should expect it also in your system. Another fault that occurs about once per week: One of the monitors will begin to display a solid color screen, changing from red to green to blue about one second for each color and continuing to do so, until I turn the monitor off and back on again. Again, it happens so seldom that it has not affected my usage of the BVU195, but it's definitely something to be aware of in making your choice. I havn't seen this particular bug reported by other reviewers.
It's only those three bugs: blinking off, blinking through colors and lack of gaming speed that causes me to give this product a 3 for performance. However, for applications like stock trading that have relatively slow changing displays using primary colors (no textures) I think the BVU195 is really a great solution because it's expandable, configurable, reliable, easy to use, easy to install and coexists with pre-existing video hardware. It's most important feature to me is the ability to independantly configure every individual monitor.
If you choose one of the less expensive USB multi-monitor drivers that are available, just make sure it meets your requirements for operating system and maximum resolution. Those particular specifications seem to be a determining factor of price.