Hey folks! I just ran across a really useful, FREE and small (1.6 MB) to help diagnose "Hey, what's going on here?" and "What's slowing me down?"
It could save you some long downtimes trying to get help from Microsoft, your PC's manufacturer, and the software company (each telling you that it's the other guy's stuff that's causing the "problem"), and will help detect "bad stuff" and let you research it more quickly (i.e. "How do I know if this is the bad guy and how do I get rid of it?").
Hope this helps!

P.S. The external link is to a review in technet. Software by Mark Russinovitch.