By 2008 I plan on upgrading this 2 yr old mobo, just hopin' for advice

I currently own a Socket 939 ASUS A8V Deluxe mobo AGP 8X VIA K8T800 PRO chipset mobo. I wonder if it would be worth my while to upgrade to a PCI-Express (2x, or 4X, or whatever PCI-E speed). I've been real happy with ASUS in terms of mobo's, and still plan on staying with AMD CPUs. I buy a lot of my periphs at NCIX stores, and was hoping readers on these forums would give me some good advice. I've set my sights on the following mobo & CPU:

• ASUS M2N-SLI Deluxe ATX AM2 Nforce 570 SLI 2PCI-E16 2PCI-E1 3PCI SATA2 Sound GBLAN 1394 Motherboard

• AMD Athlon 64 X2 5200+ Dual Core Processor Socket AM2 Windsor 2.6GHZ 2000FSB 2X1MB 90NM Retail Box

but I'm currently stuck on which GPU (Graphics Card) I should stick with. I know it'll never be an ATI! MAINLY NVIDIA GPUs do it for me. Here's a list of new PCI-E NVIDIA GPUs I've checked out details on:

EVGA E-GEFORCE 8600GTS 675MHZ 256MB 2.0GHZ GDDR3 PCI-E Dual DVI-I HDTV Out DIRECTX10 Video Card

EVGA E-GEFORCE 8600GTS Superclocked 720MHZ 256MB 2.1GHZ GDDR3 PCI-E Dual DVI-I HDTV Out Video Card

EVGA E-GEFORCE 8800GTS 500MHZ 320MB 1.6GHZ GDDR3 PCI-E Dual DVI-I HDTV HDCP DIRECTX10 Video Card

EVGA E-GEFORCE 8800GTS Superclocked 576MHZ 320MB 1.7GHZ GDDR3 PCI-E Dual DVI-I HDTV HDCP Video Card

I would be extremely grateful for the good advice.

Thank you in advance for your research and advice to help me out.
\m/\m/
~GK~