Change the windows 7 Logon Background

Hey, i want to change the logon background for windows 7
i have tried this:
press win+r key and Type Regedit at run prompt
2. Locate following registry key
HKLM\Software\Microsoft\Windows\CurrentVersion\Authentication\LogonUI\Background
3. Now in right-side pane, change value of OEMBackground to 1.
4. Now place your custom image in %windir%\system32\oobe
5. Create a new folder info and background within newly created info folder
Folder path should look like this %windir%\System32\oobe\info\backgrounds
6. Now place your desired logon wallpaper within this background folder with file name as backgroundDefault.jpg

i can edit the registry, but i can't copy the file to the oobe folder or anywhere there, because they have locked me out from editing the c:/windows folder.
is there anyway to make the registry think the %windir%\System32\oobe\info\backgrounds is say c:/users/USERNAME/Desktop/File.jpg ?

i have another restriction on this laptop
i cannot open .exe files
i can in safe mode, i tried TweaksLogon.exe but it says it cannot edit the file from the oobe/info/background folder.

so as i asked, can i make the registry think the file is elsewhere?

Are you sure you don't have User Account Control (UAC) turned on? This creates all kinds of pesky restrictions such as preventing applications from editing the registry, etc. It may also prevent you from creating folders under %windir%. Try turning that off and see if you have more success.