How old is his computer? what are the pects? chances are, if his computer is running Win98, XP will run at a snail's pace. Computers designed to run 98 have different ports such as with the amount of USB and serial, though it varies slightly, and certain features of XP may not work. At least, that has been my experience. His best bet is to get a totally new computer unless the disks for Windows 98 are still present.
You could always look at my sig, too.