XP Pro has additional commands that XP Home doesn't such gpedit. Also it has better security features. Xp Pro is excellent for networking and business and what not. Otherwise XP Home is nice and it isn't bad at all.
I've been told XP Pro is more stable overall and runs older programs better in Compatibility mode. Get it off of Newegg if you want. $141 regular, $86 if you can prove you're a student.