Managed to talk her out of wanting to play high end games like Mass Effect (she can use the other sister's PC for now), so maybe upgradable is the way to go, especially since a P4 3GHz is a POS.
I'm just worried about it being a refurb and/or it being a POS performance wise. Plus, nothing is really upgrade proof. I mean, sure PCI-E helps a lot, but CPU/RAM would become the bottleneck and they change CPU connectors every 2 days it seems.
EDIT: And if we did buy that HP, I probably wouldn't sell my parts. I'd keep them and use them for a HTPC or file dump probably.