8 GB RAM
80 GB OCZ Vertex 2
1 TB F3 Spinpoint
1 TB WD Caviar Black - location of all programs except OS
My internet is 30 down and 4 up, but I tend to get more than that.
I use XSPLIT to stream and have a personal license.
For some reason, when I stream, I don't drop frames according to xsplit, but every couple seconds my game will drop from 120 frames to 2 or something. It's like I'm playing a stop motion movie. I tried dropping quality on xsplit over and over again, eventually reaching 0, but I kept the bitrate around 2k, nothing changed. So then I tried capping my FPS at 30 and it didn't drop frames because there were no frames TO drop, so either way it was unplayable.
Assuming you've already tested your bandwidth for consistencies...
2 things you can try.
1 - Make sure you're running your 3D App/Games in full screen mode (and not full screen windowed mode). You may also want to try to enable VSync (I know it's counter intuitive but try it and see if that fixes it).