pyro, I don't know if I'm seeing what I'm supposed to see, but ...  It's quite basic and extremely plain.  Green buttons on a white background, and grey sub-level buttons. Dunno, I think you can do better than that.  I don't see any design here, just plain buttons thrown on a white page.
Also, I think you're exagering the download time issues, your buttons are way too dithered (the grey ones). Typically, a page with 100k or so of graphics is acceptable.  Don't destroy any design effort by trying to get it down to 20k.
Don't mean to be rude, just trying to give you some feedback.