You can still boot into windows, right?
If it were me, I'd make an image backup of the infected hard drive and then try using the undo delete software. Then if it recovers what you're looking for, save those files on an external hard drive and attempt a system restore by booting off the Windows 7 installation disc.
That way, if the undo delete process fails or messes something up, you can restore the image as it is right now and try something else. Otherwise, if it does work you'll have the files you want extracted and can safely attempt to restore the machine without worrying about losing your data. If the restore doesn't work properly you can do a clean install; you'll have to reinstall all of your programs as well but at least you'll have your files