"Work with" is a pretty broad question. I don't have any XP computers to test with, but I'm certain that it will work. I have both 802.11N and 5G enabled. 802.11N is supposed to fall back to 802.11G and earlier protocols if your XP does not support 802.11N. The new 5G streaming protocols are still in draft, and haven't received an 802.11 designation yet, but are likely to work with whatever is the final standard. Your XP would not be able to take advantage of the 5G capabilities, but you'll want to have a router ready for your next generation of computer (and television, streaming backup, etc.), so I would get the most advanced router that you can. Hope all of this mumbo-jumbo makes sense.
Yes very much so. It works with any web browser and you can even set it up the first time via wifi ... although its a bit easier to use a computer hooked up direct with a network cable (cat5/6). I set mine up with Ubuntu Linux. I powered the cable modem on first after it cycled on and the lights became stable I powered on the router got up and got a soda and when I got back (5 min's) I powered on my computer. After boot up I opened Firefox and just by opening the browser the Netgear setup website (local from router) was there and I used the easy setup then after that was done I went back in (192.168.1.1 into my browser address bar then hit enter the manual with it has the factory default login & password) and changed the main password / the wifi passwords and SSID's / and VERY IMPORTANT turn OFF UPnP!
To my knowledge routers are not OS dependent, they have firmware to operate them. If you get it you may want to update the firmware at some point, but at the beginning just wait and enjoy the router. BTW - For a little more money the ASUS dual band ASUS ASUS RT-AC66U Dual-Band Wireless-AC1750 Gigabit Router is the best one I have ever seen. The Netgear will work just fine.