The font - Change to Verdana or Arial or somthing That's the MAIN thing for me
The Background - I prefer it to either have a colour other than white, or to have other colours going on around the place.
The Logo - Right now, It doesnt really blend in, At all. You could do with having the logo's background being similar to the background of the page, or somthing similar to that...
The Logo positioning - If I where you, I'd make the logo slightly, and move it to the top left corner.
Also, The menu links are broken when you go from one page to another... I.E. If im on the Debian install guide, and want to be on the Ultimate install guide, I cant go directly over, without getting a 404.