Gee, i dont see any reson to upgrade your computer yet, i run 4years old computer, u have good CPU as i know, no need to change that, only if you will use it for mad running 10 apps at once...
Save your cash for now, gather little more and in few moths prices will drop.....
And for all low budget wanna have directX 10 GFX card i recommend ATI 2400, 2600, 2800 HD, they are good cards with and not to costly, all under 100$ or Nvidia GeForce 8500GT, also directX 10 support 256-512 DDR2, good bundle, price bout 80$
