2gb to 4gb? or 512mb to 896 mb?

I'm assuming this is the right section...

So, Here are my stats,

Wolfdale 3.16Ghz Core 2 Dou | OC 3.8ghz
PNY Geforce 8800GT 512mb
Kingston 1x2GB PC6400 800mhz @ 886mhz (6 6 6 18)
Rosewill 600W PSU
Western Digital 1TB 7200RPM SATA 3.0Gb/s
Windows XP Pro 32-bit

My question is, which upgrade should I make?
http://www.newegg.com/Product/Prod [...] 6820145247
or
http://www.newegg.com/Product/Prod [...] 6814125294

For the RAM, I've been told running 32-bit will only pick up about 3.2GB of the ram, I DO plan on switching to windows 7 in the close future however.

For the GPU, I may have to buy a better power supply, as it requires 550W, and I have 600W, a little close, as my 8800 requires only 400W.

Also, on a side note, I don't overclock my GPU, but it constantly runs in the 60C'S with the fan on 80%, so I'm not sure if my Ram is making it do all the work or something.

Again, the question I'm asking, is, as a gamer, would be the best upgrade for me right now and the long run. I DO plan on getting both, I'm just trying to see which bottleneck I should get to first.

~Thanks
~Kyle

But that one has 1200mhz memory clock compared to the 2500mhz on the gtx and 128bit....compared to 448bit but its ddr5 compared to ddr3, 1gb memory compared to 896, and 805mhz core clock compared to 680.

I still think the gtx 260 will be better, and also the rosewill isn't my concern, its the fact that the card needs 550W MINIMUM and i have a 600W

Yea, i think i'll stick with the GeForce series