PCSTATS has posted 99 tips for enhancing performance of Windows XP, ostensibly for beginners. BUT (read on...)

... not sure I'd actually attach the word “beginner” to many of these tweaks, although none of them are complicated if you know the basics of Windows, the registry, and other topics of a similar skill level. This is actually a pretty good list, so if you have a spare day or so, you might want to give some or all of these a try. Just be sure to set a system restore point and do a backup first. For people looking to take a step into Windows that's beyond what you can do within the UI (if you don't know what “UI” means, please skip this entire article), this is for you.

... and thanks to Jake at uttlerlyboring.com for linking to the site, which is how I found it ...