I built a system a year that I wanted to be able to play DOOM3 on at highest resolution. I went with a P4 3GHz w/HT, 1GB Kingston Hyper-X PC5400 (2x512MB) and XFX GeForce 6600LE / 256MB DDR / PCI Express / SLI / DVI / VGA / TV-Out / Video Card . It ran DOOM flawlessly and I was very impressed.

Now, I purchased GUN and want to do some upgrading to increase the performance and be able to play it at max resolution. What should I do to achieve this? Obviously, doing both would be the ultimate solution, but I'm looking for the best solution at the lowest price.

New GFX card with 512MB DDR3 memory or double my memory to 4x512MB PC5400 Kingston Hyper-X (or replace it with 2x1GB OCZ Gold or Corsair XMS)?

Any tips!

Doubling your memory will have almost no impact on performance.

Getting a faster video card will definitely have an impact.

-mpjesse

mpjesse's very right - doubling the memory will make virtually no difference.

Depending on your budget, I'd recommend you put the 6600 LE on E-bay, and get yourself a 6800GT, or even a 7800 GT/GTX if you can afford it (Albatron 7800 GT goes for $290 after the rebate on Newegg.com)

That, combined with some overclocking on the CPU (Depending on the motherboard chipset) should see you through for at least the next year.

If the budget is very limited, you could even consider a 6600GT, as it is considerably faster than the stock 6600.