Just delete everything apart from the folders that have the files you want to keep.
Afterwards, you can change the location of the Windows 7 library folders (documents, pictures, downloads etc.) to the folders on your hard drive. I you don't know how to do this - all you have to do is go to your personal folder (start, then your name at the top above documents etc.) then find the folder (eg. my documents) right click, properties, location tab, move, then select the directory on your storage hard drive.