AMD 64 is much better option if compared with Intel P4.
Cool & Quite technology keeps the processor enough cool. But, today's P4 is suffering from cooling problem. P4 doesn't posses the ability of varying its speed according to speed. Only it knows to turn off the PC when over heated.
AMD 64 is an extended 64-bit processor that is much cheaper than Intel 64-bit processor.
AMD 64 comes with special SP2 support and Intel doesn't.
3DNow! and Extended 3DNow! are available in AMD processor.
Now it's your choice.
400 watt SMPS, if true power, is enough.
For AMD64 ASUS mainboard based on nForce 4 ultra chipset is recommended.
Combination of heat sink, heat pipe & heat sink fan is recommended for your 16x PCI Express card.
SATA-II HDD is highly recommended. If possible, at least three HDs in RAID (RAID-5, if supported by your mainboard) would be better.
If possible use RD RAM. While choosing a RAM, you should be aware of the latency time factor.
My last recommendation is an Antec cabinet with a 380 watt or higher capacity SMPS (should be a true-power).
