Decrease Startup Time
In Windows XP, you can increase the start up time of many applications. This way is using the ‘/prefetch:1’ trick that Microsoft uses to make Windows Media Player open up faster. So if Microsoft Windows XP can do that to their programs, can’t we? Well of course silly!
To do this, find the file you want to speed up faster. Then right-click on it and select ‘Properties.’ Then find the box with words in it next to ‘Target.’ Then at the very end, add ‘/prefetch:1’. Just click ‘Ok’ and now you are done. Now you can test it to see the dramatic speed increase! Windows XP should now start up fifty times faster!

This is a MYTH and will do nothing.
Windows Media Player does use this switch but it is not to improve startup time. It was the author who was silly to assume this without any justification.
The following blog by Ryan Myers, a Microsoft Engineer, explains the truth:
http://blogs.msdn.com/ryanmy/archive/2005/05/25/421882.aspx
Larry Miller
Microsoft MCSA, Network+, A+