prefetch folder in C:\Windows

This Windows folder contains a significant number of .pf files, most of them created fairly recently. I believe I recall one of the Geeks saying it is safe to delete these files. I do know that CCleaner does not clean or remove them. What is their significance if any, and can they be periodically deleted or better left in the folder as is?

 

XP manages this automatically. There is no need to go in there..

 

Thanks for the tip.