http://forums.microsoft.com/technet/showpost.aspx?postid=1358057&siteid=17&sb=0&d=1&at=7&ft=11&tf=0&pageid=5

Um, everyone should have known this issue exists in Vista ...

It's either 1 of 2 things - you've all seen the Apple commercial vs the new
Vista with his big security goon?  Well, my theory is every byte of data needs
to go thru the overhead of - allow / deny - at some point in Vista's innards
lol



If it's not that - It's probably because MS has decided in their ultimate
wisdom to bend over for the media corps and DRM and thus are encrypting
EVERYTHING going to and from your system bus...  this is by design!   So
instead of copying pure data - the process is - read a few k - encrypt - send
over system bus to destination - repeat.



I'm surprized you don't know about this -read it-
http://www.cs.auckland.ac.nz/~pgut001/pubs/vista_cost.html



Vista is not going on my personal systems ever.  Period.  MS needs to get a
clue.