Then again, by the time you buy a new PSU, GFX card and more DDR2 RAM, you are most of the way to a new build. Skip the RAM. Rather than investing in upgrading old tech,(DDR2 memory) the money could be better spent on a newer mobo that will use DDR3, SATA3 and USB 3.0 That should future proof you for a few years at least.
I'm in the same boat, using DDR2 and find the cost of doubling the 4gigs I have to be way out of line with newer RAM. I'll up the RAM when I build a new rig instead.
Yes, very well said, and quite pertinent. For one, going with a mobo that supports DDR3 SATA3 and USB3 will markedly improve performance in many areas, particularly with file copy/transfer tasks. Also, DDR3 RAM is half the price of DDR2 these days, so a mobo upgrade to support DDR3 would save money there alone.
Furthermore, most modern motherboards have headers to support front USB3 and eSATA ports, which is real handy and saves a lot of messing around getting at the ports on the rear of your case. I have these built into my case, but they can be added to any spare drive bays via add-ins.
The other thing to consider if you're going to do a rebuild, is whether you're going with Intel or AMD. Now there are some fan boys who will tell you to go one way or the other, but at the end of the day it's what you're comfortable and happy with... what's in your price range. I am not a fan boy, but price-wise I have gone with AMD for a few years now and have been more than happy with my choices. I currently have an AMD x8 8170 Black Edition and it is not only quick but very reliable/stable. Yes, some fans of the Intel i7, i5 series CPU's will tell you that Intel has faster CPU's than the 8170, and that's true, there are faster some Intel models, but at the same time there's a lot of slower ones as well.
So yeah, think of your needs and what you can afford, then research what's available to meet those needs within budget and go with those components you're happiest with... be it AMD or Intel, ATI or Nvidia.
Oh, and before I go, with regard to the PSU, while Corsair are a good reliable brand, Gigabyte, Silverstone and Thermaltake do some pretty decent PSU's at affordable prices as well. I have a Silverstone 1200w and it hasn't missed a beat since installation 6 or so months ago