I think an uber high end rig is overkill for your uses (4 gigs of RAM just silly!), but if you really want to
TBH I would go A64 - the P4EE is a total waste of money - A64's can do most things better (apart from encoding). For the less than the same price as the P4 same price you could get the FX-55 (the top of the range A64) and whatever board suits your requirments. Couple it with two WD 74gig raptors in a RAID1 array and whatever RAM you like; and you have a extremely fast PC
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A more sane approach would be an A64 3500+ (less than half the price!) and whichever board suits your needs, 2 gigs of RAM (even that's a lot) and keep the two raptors. It would still be very fast, and pocket the rest of the money and spend it something nice like a big monitor