Processor Bottleneck?

you are testing it wrong, you are using gpu stessful res's when to test cpu 's you use as low a res as possible.

if you stat at 12 x 10 and move to 10 x 7 to 8 x 6 and your fps does not change then you have a cpu LIMITATION but only if you get unplayable fps is it a bottleneck. if, at low res and settings you don't get playable fps then yes, a new cpu will help.

It's the Pentium D, they are really terrible dual-cores. I was in the same situation as you and I upgraded to an Athalon x2 5000+ @ the same clock speed (2.66Ghz) and got a massive FPS boost. I suggest you go with something like an E6750 (~$189) if you can afford it though. Basically just stick to Core2Duo or Athalon X2

Vista is going to effect your load times most likely. You'll also want to read some tweak guides and disable a bunch of useless services that are enabled by default.

Cool, I hope they deliver.

About Vista:

You may see lots of HDD usage for a few hours after installing Vista because of it's indexing service. Also, Vista has an automatic defrag feature that either runs weekly or bi-weekly (can be disabled). Just some things you may or may not be aware of, I figured you'd like to know if you didn't already.

your processor may not be the best but have you tried lowering the res like i suggested, you are not currently testing your cpu. going to a new cpu will do damn all unless you are sure you are not gpu limited.

after a bit of searching(toms you ahve really fukced up by leaving out quick links to the old charts) i found this, AFAIK, the 7900GS is about equal to the 7800gtx so it might well be gpu

http://www23.tomshardware.com/grap [...] 2&chart=82