Can't password protect folders in XP home like in pro or even Win 98. If it is shared, anyone on the network has access to it. Very weak feature to leave out of XP home, when Win 98 even had it.
Also, once you go over 5 PC's on your home LAN, XP home gets a bit buggy in file sharing and although rare, occasionally finding/ connecting to games through ingame browser. And PC building is addicting right, so it's simple to go over 5 PC's. XP Pro on the other hand is good up to 10 PC's peer to peer, and yes also on a domain based network as you stated. If you are a college student and hope to connect at school without hassle, you would want pro.
ABIT IS7, P4 2.6C, 1GB Corsair XMS 4000 Pro Series, Radeon 9800 Pro, Santa Cruz, TruePower 430watt