I believe that you could copy the files in windows explorer (provided all files are shown, nothing hidden including hidden files and windows configuration files, etc, therefore EVERYTHING) and then use tweakUI. You would have to change the path of shortcuts very likely, and I am sure that there should be many things you would have to reinstall.
If you are running out of space on that partition you can always create another Program Files directory on another partition and then just use that from now on, but probably the best solution is to resize the partition with partition magic or drive image....