Well if you're looking for expensive, which you are (with an X800XT Platinum), then a P4 system (HT) is your best bet. Personally, IMO, you can get a GREAT system going with an athlon XP, with amazingly stable mobo's from ABIT. I'm gonna throw out a system here, you can take it or leave it, but its amazing for the price, and you'll love the stability and blazing fast speed.
ABIT NF7-S 2.0 <---one of the best mobos for almost a year now, check any review, you'll see + its cheap $99 or less
AMD Athlon XP 3200+ <---great processor for the price, and you'll spend half of what you'd spend on a damn P4...
512MB-1GB Corsair XMS PC-3200+ <---depending on what you want to spend, and if you want to upgrade later, decide between 512 and 1GB...but you cannot go wrong with a corsair paired matched memory...
and if you really want that graphics card, then go for it, you CANNOT go wrong with it, its truely amazing...minus the price...(if thats even an issue)
anyways, all of this is going to suit your needs great, and for a fraction of the cost of a typical P4 rig...but again, this is my opinion...but i've done my research plenty of times. Check that out, lemme know and I'll help ya out if you want different parts. I wont stear you wrong. Oh, and one more piece of advice...
SHOP AT
WWW.NEWEGG.COM
you cant beat their shipping rates, and prices are lower than anywhere else (99.9% of the time)