There are NOT any major differences in performance between XP Pro and Home. XP Pro adds Remote Desktop, which you don’t need. XP Home only supports one processor, XP Pro supports two. Pro supports dynamic disks, which doesn’t effect you. There’s lots of other things, mostly networking related, but for your application, XP Home should be fine. I don’t know if the multiprocessor support would be an issue for you if you are using boot camp, because it would be a shame if you could only use one processor from Windows and two from OSX.
Tim