What you are looking to do is called a V2P migration. (virtual to physical) and can be very tricky.
Your best bet is to reinstall W7 in Boot Camp, migrate the files and programs you need over and then open your Boot Camp install in Parallels.
If you bought an OEM/System Builder license for Parallels, you may be in trouble as it is tied to the first machine it sees. You may (or not) be able to activate it in Boot Camp, but your right to move it is not explicitly given by the EULA.