So here's my situation. I'm upgrading pc to play gears 4. I needed more ram, got that in there. Now I need more video memory (4g minimum) and its my understanding that's my graphics card? So right now I don't know if I even have a graphics card but it says I have 2g of video memory. I have a ibuypower I series 301 pre built. Quad core procceser 300w battery. I'm trying to spend under 250$. What are my options?