Help on a computer

[Iceviper]

This is going to be a multi part question and I appreciate any and all advice

Im going to buy a new computer solely for gaming, but im not going to spend more than 1100

Ive narrowed it down to these options using AMD as ive heard they are preferable for gaming:

AMD 939 Athlon 64 3200+
Abit AV8 via
1 Gb Corsair XMS
WD 80 Gig (not sure if can get SATA with my board)
GF 6800 Pro 8X AGP

or

AMD 939 Athlon 64 3200+
MSI Rs46on2-IL ATI
1 Gb Corsair XMS
Seagate 80gb (SATA)
GF 6800 256MB PCI Express

So my questions are:
is the athlon 64 worth it over a athlon xp?
are the board options ok?
I like corsair memory alot, anyone have any problems with it?
Is SATA harddrives important?
and the biggest question...Is PCI express better than AGP? i know you can dual video card pc's with pci express and SLI technology, but if i dont plan on doing that should i just stick with agp?

thanks

 

[Iceviper]

Ok i updated this a bit after reading some other posts so it looks like this now:

AMD Athlon 64 3000+ (939)
MSI "K8N Neo 4 Platinum SLI" (which gives me options to double video if i ever find the need)
512 MB Twin Corsair XMS with Plat. Heat Spreader
Seagate 80Gb HD
Chaintech GeForce 6600GT

I got this to be valued at about 1000US from New Egg, and was planning on building it myself to save cost, but then I looked up this system on Cyberpowersystems.com and it was almost the exact same price...does that sound odd to anyone else?

Anyhow any comments or upgrades or better places to find deals would be appreciated advice