I've used Arduino Uno a little over a few months with no driver problem on XP (Intel Atom) and Win 7 and 8 (Core 2 and AMD).
I wanted to alter Arduino programs in "the field" with a small XP (Via C7-M) laptop but the drivers will not install, leaving the serial port greyed out under the Tools menu.
Can anyone tell me if drivers are available and if so where?