Hmm. If you're going for a top gaming machine, you've got a good start. I won't comment on the price, just the equipment choice.
1) The 3400+ Athlon64 is a better buy. Nearly as much performance (within 5%) and about $300US cheaper. You're going to have fun finding one, though. It's early in the product cycle.
2) Mobo is okay, though I'm not a fan of VIA chipsets.
3) Good RAM choice and case.
4) No doubt you know that the GF 6800GT isn't as fast as the 6800XT. If you go for the 3400+, you should have the money for the faster video card.
5) I would go for a 480 watt power supply, minimum. The 64-bit CPU's are power hungry. Same for the video card.
6) If you buy the retail version of the CPU, then it comes from AMD with a CPU cooler.
7) The best DVD writer around is the new Plextor 712A (faster version of the current 708), as anyone will tell you.
Is it better to wait for PCI-Express to come out? It depends. If you don't mind waiting until the end of the yaer or so for PCI-X mobos to come out and then to get down to your proce level, then it's a good idea.