Hi,
Yes, Windows XP is faster and more stable. It has better compatibility with older programs and is generally easier to use.
Also, the obvious one... Its the latest and so you wont need to upgrade again for a greater amount of time.
Now for the downpoints... Its possible that some drivers for older hardware wont have been re-written for XP and the Microsoft supplied drivers wont work or at least may be missing some functionality as they tend to be more generic.
This is unlikely, though. I've had no problems myself but it would be worth checking out before you decide.
If you're planning to network in the future, then go for WindowsXP Professional. WindowsXP Home has more limited network capability. It was designed that way.
Hope this helps,
Cheers,
Tim.