If you are still expeiriencing issues with the install then read the following. i copied and pasted it from one of the other posts that i replied to.
I installed windows 7 on my iMac 27" late 2009 about 2 weeks ago and it works fantastic however the process was not easy. I encountered a problem and had to try it several times before i found the solution. Even Apple Technical Support wasnt able to fix the issue, they were blaming the install disc.
Download the pdf for bootcamp on another device
http://www.apple.com/support/bootcamp
or print it so that you can refer to it if something goes wrong. Now if you r using the same machine as me or iMac 21.5 mid 2010 model, then you will have to do one extra thing. You will encounter a black screen when the machine is trying to configure the windows os and to avoid that issue follow the instructions in the link below. this happens because the windows os is not able to locate drivers for the display, hence nothing is displayed on the screen but the os is running in the background and waiting for you to put your information in such as name, etc.. Also one main thing make sure you are using a usb powered mouse and a keyboard.
http://support.apple.com/kb/TS3173
Hope your install does not give you issues like the way it did to me.