CCleaner

I like my laptop a lot, but it's Mobile Pentium III was starting to wheeze under four years of built up detritus. And this was with Norton AntiVirus and the very handy NoScript plugin. So despite my best efforts there was a 3 second pause anytime I opened up a folder in desktop explorer.

My IT guy at work, a gentleman and a scholar, recommended I run CCleaner, which is a freeware system cleaner and optimizer. It helped a lot.