One of my biggest pet peeves about Vista is the lack of a run as option from the right click context menu. Not having that means I have to RDP a server just te unlock a user account or change a password. Finally Microsoft realized this was an issue and they sent Mark Russinovch in to save the day! Here's a link to the Shell Run As Utility that restores the menu. Enjoy!
http://technet.microsoft.com/en-us/sysinternals/cc300361.aspx