When testing security in SharePoint/Reporting Services you want to run IE as another user, I run my laptop and VM’s on Windos Server 2008, the runas feature has disappeared from this release. But SysInternals has a tool who puts the “Run as different user…” option back into the context menu for applications
You can download the tool from HERE, (which comes as a ZIP file containing the EXE and a licensing agreement), and run the exe from an “administrator” command window like this…
Shellrunas.exe /reg
Found this tip here:
http://blogs.msdn.com/normbi/archive/2008/04/26/adding-runas-back-into-vista-and-windows-2008.aspx