I'm not running xp myself, although I plan to put it on my second rig, however a friend of mine has been constantly complaining about it being "slow" and I know that system restore does have a bit more overhead.
However ntfsdos pro has been used a couple of times to restore a working good registry from the system volume information\_restore dir, and this is the big thing that is really useful, as it will create at least 30 registry backups.
One of these days I need to clear one of my partitions and slap xp pro on, granted those that know me, know I've been saying this forever. 🙂