Height: 450px
Width: 1900px
EXACTLY 950px of WHITE SPACE in the middle
Columns on each side of the white space (Like the old RuneScape website's columns but more stylish, maybe like electric bolts, I don't know) around 30px wide going down then fading into another darker colour (Like http://www.bungie.net ). I'm not sure what to have in the remaining space, pm with any ideas you may have. Also try to keep it RuneScape..y (Lol) nothing to futuristic?
Format: Not sure - A balance between quality and file size, seeing as this is going to be the background for a website it needs to be as small as possible.
Feel free to ask for any other info you may need.