Would this be there major bottle neck in my PC? Also, should I go with 1gb or 512mb. I only play DOD: Source and CS: Source... and not all that often. I am a software developer and run visual studio and eclipse all day everyday. I am running windows 7 on my old comp and Linux in a virtual machine. What do you guys have to say? Maybe I could get a way with an i3?
It depends on your monitor resolution. If you are using 1360x768 then the 9500GT will play just fine but a medium setting most of the time depending on the game. Any resolution higher you have to get a better one.
Get the 512MB version since a 9500gt can not really make full use of the 1GB memory.
You'll regret getting such a weak video card and will be limited to very old games or low resolutions.
I'd go for a cheaper processor (AMD Athlon X4) and upgrade the video card to an ATI 5770 or at least an Nvidia GTS250.
I doubt you'll notice the difference with a cheaper CPU for visual studio, eclipse or VM's if you stick with a quad core.