I've been getting some frustrating behavior from (File) Explorer in Windows XP while working on a video project. Selecting an AVI file spikes the CPU and locks the file for 30 seconds or more. If it's a corrupt AVI file, my computer can hang for several minutes. I finally tracked down a way to disable whatever preview or statistics Explorer is building. I'm not sure what else it impacts, but so far it's been great. Now I can move and delete video clips without an aggravating pause.
To remove media preview, run: regsvr32 /u shmedia.dll
To restore media preview, run: regsvr32 shmedia.dll