I couldn't show you a computer that I would say, "This is what you need" because at that low of a price, it depends a lot on what you're doing.
If you're gaming, you'll want a lower end CPU and RAM, and go for a good Video Card.
If you're doing photo or movie editing, the CPU and RAM are going to be more important.
I have made several setups on cyberpowerpc.com that were under $700 if I went with AMD, but then again, that is normally considered a lower end company that Intel.
Thanks so much! I ordered one on CyberPower for $720.00. It has an AMD FX 4100 3.6 GHZ Quad Core CPU, AMD Radeon 7770 1GB, 8GB RAM. Its a very good price for that good of a computer. It runs 82 FPS On Ultra on COD: Black Ops 2. Thanks for the help man! Really appreciate it!