You have a usb wireless. What happens when it is not working, you then unplug it and then plug it back in? I haven't used xp for a few years, so memory is shaky. It really sounds like the usb port is shutting down in hibernation and not waking up. It would be easier sitting at your keyboard:-) Have you loaded any new software in the last few weeks? Can you do a system restore to the time it was working.
Try plugging the wireless into a different usb port. The driver would be installed for that port also.
The link you gave is probably OK. The same driver is available on the linksys/support Web page. It should be safe there.
