I use linux mint 8, and I want to change the background for the login screen. For easier and smoother login. Ive googled for days,cand nothing works. I tried GDM2 and I press select new image, but it doesnt work. Do I need the image in a certain folder? Is there other ways to do this?

I did this in Ubuntu 9.10, so it may work for you:

1. Logout of your current session and return to the GDM
2. Switch to the tty command line prompt using Ctrl-Alt-F1
3. Login using your normal login/password
4. at the command line prompt type: export DISPLAY=:0.0
5. then type: sudo -u gdm gnome-control-center
6. Switch back to the gdm screen using ALT-F7
7. The gnome-control-center should be loaded. Use it to configure your GDM.
8. Click on the Appearances icon, in appearances you can change your GDM's font, theme and background image.
9. Close the gnome-control-center and login normally.

That kinda worked. It shows it at login. Its just that linux mint shows it's default background as a splash/ loading screen. How do I change that?

Hey there! I figured this out...

There is a symlink called default_background.jpg in the directory:
Which links to the file:
Which is in the directory:
You are able to change the background image on the login screen by replacing the file gelsan_green.png (or changing the symlink, which is probably preferred over changing the distro files!), located in:

The image has the dimensions of:
1920 x 1200 pixels

and it's a .png. hope this helps!

Cheers!