Issue with Bootcamp 5.0 and Windows 7: Ultimate 64-Bit Install

HERE are the specifications of my iMac.

I am trying to install Windows 7 Ultimate 64x on a 150GB partition i created using bootcamp 5.0. I get to the point where it finalizes the windows setup, and then it says "Setup Up Desktop for first use" or something of that nature, it restarts then, and goes straight to a black screen with a black cursor. I have tried to get to the BIOS to change the boot order (thinking it may be something to do with the boot order) but I won't even let me access that! Any fixes would help a lot!!

I was using parallels before this, but I want a seperate partition so I can play games that are too high demanding (graphics wise) to run in a VM, the crash on start every time. Some run, but very choppily.

Also, I am running the latest edition of mountain Lion if that helps...