can i delete the data in the prefetch folder ?

Each time you turn on your computer, Windows keeps track of the way your computer starts and which programs you commonly open. Windows saves this information as a number of small files in the prefetch folder. The next time you turn on your computer, Windows refers to these files to help speed the start process.

The prefetch folder is a subfolder of the Windows system folder. The prefetch folder is self-maintaining, and there's no need to delete it or empty its contents. If you empty the folder, Windows and your programs will take longer to open the next time you turn on your computer.

Dangerous myths: Deleting the informaation in Prefetch folder
=============================================================

There are often claims that deleting the Prefetch folder actually results in less boot-up time and more free memory. The reasons for this vary—for example, some experts claim that Windows loads Prefetch information for all of the programs you’ve ever started on your computer into memory automatically, filling your RAM with unused data (this is not true.) These experts recommend deleting the contents of “Windows\Prefetch” on a regular basis, to keep your memory free from unused data. Ouch! Two reasons:

   1. If you don’t run a program, Windows does not access the Prefetch information.
   2. Windows maintains a maximum of 128 entries in the Prefetch folder. It cleans itself automatically.

So, if you actually delete the Prefetch folder, here’s what you should really expect to happen: Windows and applications will need noticeably more time to start, as the Prefetch data needs to be collected again. The entire performance of your system will slow down.