XHTML...valid!
CSS...valid!
Yay!
Your site works perfectly in Firefox 2, Opera 9, Netscape 9, and Safari 3 beta for Windows. In Internet Explorer 6, IE 7, Maxthon 2, and Sleipnir 2.7, the footer only goes as far to the right as the synaptic.png image, then stops (actually, it stops a few pixels before the image). In addition, in IE 6 (but not the others) there is a pixel or two of space between the top of the navigation bar and the white area above it. Despite these minor glitches, the site still looks very good.
In Internet Explorer 8 Beta, however, there are three glitches: first, though the footer does properly stretch across the bottom of the page, the copyright is bumped to the left, as if the footer was still not extended (the "All Rights Reserved" text remains properly placed). Second, and far more important, the Contact link in the navigation bar jumps down from it's place and ends up halfway out of the bar. Third, the word "Overview" at the top of the page jumps way off to the right, so it appears after the contact link (probably related to the contact link's hop downward).
I took a couple screenshots of the glitches so you could see exactly what I mean:

For some reason, I can't get Lynx to start right now, so I didn't test in it - if I can get it running again, I'll give it a run and post if anything comes up, but I'm pretty sure it'll work great, as your site is very well laid out both visually and code-wise.
Which brings me to the design itself, which, by the by, is great. It's very clean, readable, and good-looking, and definitely has a "Linux-y" look.
I agree with casablanca about the navigation bar - the white hover is too harsh when used in conjunction with the glossy bar. Something like a glossy white/grey or even light-grey/medium-grey hover state would be much easier on the eyes without looking "too fancy." I'd also, personally, remove the word "Overview" from the top of your page content, and just have it start out with "Welcome to Linuxbootup." I think it's fairly obvious that the area is an overview, and with the welcome right under it, it seems a bit redundant.
Other than those two things, though, I wouldn't change a thing. It's great!
On the content end, one thing sort of nagged at me: who is your target audience? You seem to put of lot of emphasis on the "user-friendly" point, which makes it feel a bit like you are aiming at people who are a bit more inexperienced, while at the same time, you mention repositories, Debian, distributions, and a few other things that, though they certainly make total sense to the majority of your visitors, might confuse a few "Linux n00bs" who are likely to hit the site up based, again, on your emphasis on the user-friendliness. Obviously, I've only seen one page, so I'm this bit comes purely from a glance without knowing for sure what the rest of the site will be like - and I could very well be over-analysing.
Also (and totally beside the point): "...your days of hassle with viruses, intrusions, spyware and the like is over..." should read "your days of hassle with viruses, intrusions, spyware and the like
are over."
Overall though, despite all my nit-picking, I really liked both the design and the content. It's readable, clean, understandable, and it looks good. Excellent work!