Athlon 64 vs. P4 /w HT

I'm designing a new computer and I'm at a standstill right now because I'm not sure whether to base it around a P4-HT or an AMD 64bit.

Why am I stuck? Well, you get PCI-Express with both types. But Pentium doesn't make 64-bit processors. And AMD doesn't have an Athlon 64 MOBO out that supports DDR2!

(As you can tell, I'm a gamer.) I just don't want to sink $2500+ into a system that ends up shortchanging me in a major area.

I want a 64-bit cpu, DDR, and PCI-express all at the same time but I can't have it! What do I do?