Ok, I got the desktop background of an awesome looking cityscape.

Now all I need is the loading screen and login screen. Anyone got any brilliant ideas?

Surf themexp.org, you'll find something.

Beware themexp.org

their so called "wrapper" includes spyware.

try deviantArt. They have higher resolution and much better artists that themexp.org IMHO. They're a little slower though, but it's not that bad.

On themexp.org, just avoid any downloads that have an .EXE extension. Those are the spyware-laden ones. But Dash is right; deviantArt tends to have the better artists and cooler work.