It doesnt require installation, and wont change any of the system files.
If you dont want to use the standard Windows backgrounds, you might add your own folder of images.
After youve selected the background you want, hit the Apply button in the upper right hand corner.
Click Yes on the authorization screen.
Click Yes to User Account Control if it comes up.
The wait a bit while the background is applied.
Its easy to use and has a nice amount of features for tweaking the background.
Download Windows 7 Logon Background Changer
Windows 7 Logon Background Changer Homepage
