Change Default Folder Locations...

You can change or delete the Windows mandatory locations of folder like My Documents:
1. Open RegEdit
2. Go to HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Shell Folders
3. Change the desired folder location, My Documents is normally list as "Personal"
4. Open the Explorer and rename or create the folder you wish.
To change the desired location of the Program Files folder
1. Go to HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion
2. Change the value of "ProgramFiles", or "ProgramFilesDir"
Now when you install a new program it will default to the new location you have selected.