The prefetch folder is a cache folder. It contains info that links to recently used programs and files. It is the first place that the OS will look when you want to open a program and / or when your system boots. It speeds both.
Prefetch is enabled by default.
For more detailed info you can do a search on google.
nysaga - not a big deal either way. If they are old files, then by all means take TwoZ's advice and delete them - it cannot hurt anything. As I said, my prefetch seems to manage itself, but perhaps some don't.
Ep, glad to see you come back and tidy up...did want to ask a one day favor, I want to enhance my resume , was hoping you could make me administrator for a day, if so, take me right off since I won't be here to do anything, and don't know the slightest about the board, but it would be nice putting "served administrator osnn", if can do, THANKS