Input for a new digital dark room

[AlanSr]

I will be building a digital dark room in the next month or 2. Everything I've read shows me that I need to go duel intel or amd.
I'm looking for some input on what I need to build a monster!

I will be using XP Pro
My main program will be photoshop CS and a few other less power hungery photo programs.

Just off the top of my head I'm looking for at least
500GB harddrive
between 2 and 3GB of ram
and duel processers.

[AlanSr]

Also MAC is not out of the question.
The only draw back is I have read that there are quite a few problems getting some software to work on mac.
and then there is the price issue

but PC can't toucht that new duel G5 and you can put up to 8GB of ram in it!!!
"that would cost enough to send a small country into finical ruin"