Great work weilander:
You have provided very good suggestions.
"Short answer, nothing will ever be good enough for everything forever. "
And his comment about dated MB, USB3 and SATA6. Try to build a system that, although will be outdated in a Year, that you will be happy with for tree years. Building a system that is already very dated (DDR2) just does not make much sense.
These comments should give you some "Good food for thought"
I know you are limited in your budget and where you are buying from. you do NOT want to buy/build a system that within a year, you may regret.
USB3 and Sata 6. Not a big issue, TODAY, for you - But will be down stream. USB3 thumb drives are starting to appear and will probably be mainstream in a year to a year and a half. USB3 will also provide a Big boost for any external HDD (Note about the same as esata). SATA III (6) - NOT an issue as None of the current HDDs (even ones currently billed as SATA 6) will really benifit from SATA. BUT in a year - two. SSDs will start to come down in price, and they are SO MUCH faster than mechanical HDD. Remember the HDD is the biggest bottleneck on day-to-day usage. With SATA 6 SSD coming out, that should drop the price of SATA II SSDs
ON GPU/CPU. Since your emphasis is on gaming, bear in mind the CPU is much less important than the GPU. important than your GPU. I would think that you would benifit using your GTX 250 and downstream get a new single GPU (ie 5770, or nvidia equivalant), then still later you could sli/xfire that card.
Here is a link to GPU performance, does not show the dated GTX 250 (which is less than the 5770. Does the 250 support DX 11 - not to important today???