Steam Problem, any help would be grand!

[SerenadeShotgun]

Okay, so for starters, and i can't stress this enough; I am NOT exactly computer savvy. I really don't know that much, so it may be frustrating helping me. But basically, I've been able to play the Penumbra series, but I cannot run Amnesia. I ran a check to see if I could play it, but my video card doesn't meet the requirements. I downloaded the demo to try, on lowest settings, but just got a black screen. So here's what I'm working with;


CPU Speed: I have 3.1 GHz
RAM: I have 8.1 GB.
OS: I have Microsoft Windows 7 Home Premium Edition Service Pack 1 (build 7601) 64 bit
and the video card i have is Intel® HD Graphics Family


So essentially I'd just like to know which graphics card would work with my computer, and could run amnesia well, and preferably a good quality one, but not too expensive, the cheaper the better! So if any more information is necessary I'll do my best to give it, and any help would be greatly appreciated, I really want to get into Amnesia!