It is such a shame that cardbus is going the way of beta tapes. I've always found them to be much more reliable than the flimsy usb wireless adapters on the market. If you have an older machine that actually still has pcmcia slots, this thing is great.
If you insert the device and let Windows XP recognize it and search for drivers, you may be disappointed. I could not get Windows to recognize the driver files even when I pointed it to the exact folder on the CD. However, simply ignoring XP's insistence on installing the device itself and clicking on the "setup" application on the CD seems to solve the issue. The CD will unfortunately also install its own proprietary software for managing wireless connections, but you can still use Windows' default wireless connection software if you want.
After some installation issues that possibly wasted a mere 5 minutes of my life, the card picked up my router right away and connected at 54mbps (sadly, that's the maximum AT&T currently allows from its 2WIRE brand gateways). The piece of plastic USB garbage I bought from Linksys for $40 only recognized my router sporadically before it literally fell apart (seriously).
Bottom line is as such: I have a ten-year-old laptop with a Pentium III processor and 256mb of RAM that now has working high-speed internet.
I hate to steer people away from Amazon, but their partners at geeks.com, the people who actually ship this device, will sometimes drop the price to $5.99 on their website. That's why I don't have that reassuring "Amazon Verified Purchase" banner above my review. So if you need wifi on an old laptop and you're here, check www.geeks.com before putting this in your Amazon cart. You might save a couple bucks. For this cheap, you really don't have much to lose.