Compatibility of webcam with the Operating system

For reference, newegg.com is a reliable on-line computer supply house (not the only one; I'm not affiliated with them).  Whichever on-line site you buy from, look at the customer reviews (feedback).  Reviews are not completely indicative of a particular product's quality -- people with complaints probably post reviews more than people who like a product -- but they can give you some idea of what to expect.

I can't tell very much from the numbers on your wifi adapter (the MAC number might have provided some clue), but I have two comments about it: 

(1) As I suggested in my initial response, it's entirely possible that the device you bought was intended to be "compatible" with Windows XP and was just defective.

(2) I suggest that you think twice about USB wireless adapters that look like USB flash drives (or are smaller). As the name suggests "wireless" devices are radios and radios need antennas.  You can't get much of an antenna in a 2"-long USB device (much less in a 0.5-inch "mini").  And things are worse if you have a desktop or tower computer with the USB wifi adapter plugged into a port on the back and sandwiched between the computer and the wall. 

USB "dongles" are probably OK for laptops because you can move the laptop around to get a better signal (the selling point of the "mini" variety is that you can leave it plugged in and not worry about snapping it off), but for a desktop or tower, try to get one with a cable (either a USB cable or a cable for use with a detachable antenna) so you can position the antenna for best transmission and reception.

Read the description of the product.  If the website doesn't specify, either go to another website or email/telephone for information.

Most web cams sold today should be compatible with Windows XP (sp2 or sp3), Vista, and Windows 7.

Out of curiosity, what USB wireless adapter did you buy that is not compatible with Windows XP?  "Didn't work" doesn't necessarily mean "not compatible with" -- it's always possible to receive defective computer hardware.