So after installing Photoshop CS2 I decided to test it out. After 1.5 hour of work I end up with this:
Wallpaper #1 (resolution 1024x768):

PSD File (12MB zipped):
http://trem.walpaper.psd.patrz.pl
Wallpaper #2 (resolution 1600x1200):
[=8pt](click at the image to see it's real size)[/]
I didn't add wallpaper #2's .psd file, because it has almost 40MB and it's not much different from smaller one (I just replaced lower resolution texuters higher resolution ones and resized the "logo"). All textures from CGTextures.com, Tremulous logo from data-1.1.0.pk3