I have often seen references to some MS tool called Boot-Vis that provides a set of graphs showing you how your PC performs on boot-up.
It enables you to improve your bootup speed because it shows you what actually goes on and does it in a visual style.
The thing is, every link I've ever seen to this has been disabled or the software was yanked for some reason.
Well, after searching for two years, I found a working version and it's fantastic.
http://www.kellys-korner-xp.com/xp_tweaks.htm
Go to number 31 Windows XP Startup - Boot Performance
I have never seen another tool that provides this kind of information and I'm seeing some stuff in my bootup log that doesn't look like it belongs here. This might be a good way to find malware.
In all fairness, there has been a lot of controversy about Boot-Vis, so before you run it, you might like to do a Google search and see what you can find and then decide whether you want to run it or not. Myself, I'm just so happy to have finally found a working version (after searching for years) that I just ran it and can't believe the nice output graphs and charts it produces. I think it's worth getting just to see how they do this.