G5Unit, if you use newegg.com Wish List feature it would be much easier to review the system you are considering purchasing as you could just provide one link.
I recently built my sister a system - just a few months back. Here is what I used:
* Antec Solution SLK3000-B Black Steel ATX Mid Tower Computer Case - $49.00 (I really liked this case, simple and easy to work with)
* CHAINTECH VNF4/Ultra Socket 939 NVIDIA nForce4 Ultra ATX AMD Motherboard - $93.00
* Leadtek PX6200 TC -64 Geforce 6200TC Supporting 256MB DDR PCI Express x16 Video Card - $69.00
* Rosewill Value RV450S ATX 450W Power Supply - $29.99
* AMD Athlon 64 3000+ Winchester 1GHz FSB Socket 939 - Retail - $146.00
* CORSAIR ValueSelect 1GB (2 x 512MB) 184-Pin DDR SDRAM DDR 400 (PC 3200) - $77.99
* SAMSUNG SpinPoint P Series SP1213C 120GB 7200 RPM Serial ATA150 Hard Drive - $80.50
* Logitech Internet Pro 967450-0403 Black PS/2 Wired Standard Keyboard - $10.00
* Logitech Premium Optical Wheel Mouse Black 3 Buttons 1x Wheel USB + PS/2 Optical Mouse - $11.50
* LITE-ON Black IDE DVD Burner Model SOHW-1673S BK - $56.99
Subtotal: $623.97
Tax: $0.00
Shipping: $43.79
Amount Paid: $667.76
FYI - all these prices are from about 9-10 months ago, they are not current. I just posted my old invoice info.
I would think a similar system, with some obvious modifications would be fine for gaming. I built this system before the Venice core chips came out, get a 3000+ Venice core they are great chips, especially if you want to overclock it - plus this chip is only like $130 right now. Obviously you'll want to get a better graphics card - the new 6800 GS cards look awesome for the money. You'll probably want a beefier PSU if you're going to have a more powerful card, overclocking and/or will add more cards/drives in the future. Throw in an Audigy card with that and you have a good gaming system and it should only run you about $1000 sans display. You could also up the RAM to 2 GB for not much more money.