Easiest way, if you did a full install and actually partitioned your drive would be to load your computer from the windows 7 disc (if you have it) and go to "repair my computer" then go to the command prompt and run bootrec.exe /fixmbr and then bootrec.exe /fixboot. Once you've done that, restart and you should be OK. Just go into your drive management console and extend your windows partition (you should have, I believe 3 black bars indicating free/unused space.) This is all off of the top of my head, but I've done it a few time, no issue.