First of all, an all-around very nice looking site--crisp, clean design, well organized, the code looks pretty clean, and the graphic design is understated but elegant. I particularly like the partially outlined section headers in the righthand column (with the darker grey border on the top and to the left)--I tried to pull off something similar once, but it didn't come out looking nearly as nice.
Now, a few creative-criticism nitpicks, since you asked for input:
Mainly, I agree that you should stay away from the fixed witdth--the whole point of the web is that it's a fluid medium, so coding for a specific window width goes against the grain, so to speak. If you must do fixed, 1024 is pretty big, despite the temptation--if your (obviously very specific) audience uses big browser windows and huge monitors, it's not as much of an issue, but I have a big monitor and still run my browser windows smaller than that usually.
Three other very small things: One, in the menu on the left, having the section of the page you're on with underlined text the same color as active links in the page body while all the active links are black and plain is just a bit disorienting--it looks like the only non-link on the list is the only active one at first glance. I generally prefer obviously-marked links and a consistant link-vs-text colorscheme, but if you want to use that design style maybe marking the current section with an outline box or highlite color, instead of underline, would help.
Two, in the gecko engine the grey box toward the top with the "English - Deutsch" selector in it has a disproportionately thick border on the right. It's not in Safari, so it might just be a quirk, but that probably indicates something slightly out of whack with the <div>s.
Last, the pages almost validate, but not quite; the SGML characters are forgivable, but it looks like you forgot to close the <a> tag on the Sponsor link at the top.
All around a cool site, though--wish I had that kind of design skill.
