Kelly Theriot has put together a comprhensive site about Troubleshooting Windows XP.
My favourite bit is XP How To’s but there is a lot of really good info here. At least it’s a bit easier than trawling through the Microsoft Knowledge Base.
Another interesting read (Geek Alert) is the Windows XP Security Guide Chapter 3: Security Settings for Windows XP Clients .
It describes in detail the primary security settings and recommended configurations for each setting to secure computers that run Windows XP Professional with SP2. I rather like the line “When you consider the security policies for your organization, remember the trade-offs between security and user productivity. Although users need protection from malicious code and attackers, they also need to perform their jobs without overly restrictive security policies that frustrate their efforts.