User Account Control.  I have included 2 links which describes what it is and how to work around it. 

http://en.wikipedia.org/wiki/User_Account_Control

http://technet.microsoft.com/en-us/library/cc709691(WS.10).aspx

I, myself, am not running Vista/Windows7 just yet.  Hopefully the articles will help you out and perhaps someone else may chime in with further instructions.