Vista+ Command Prompt RunAs…

runas /user:”domainusername” cmd.exe or explorer.exe

Runas Syntax

Examples
To start an instance of the command prompt as an administrator on the local computer, type:
runas /user:localmachinenameadministrator cmd
When prompted, type the administrator password.
To start an instance of the Computer Management snap-in using a domain administrator account called companydomaindomainadmin, type:
runas /user:companydomaindomainadmin “mmc %windir%system32compmgmt.msc”
When prompted, type the account password.
To start an instance of Notepad using a domain administrator account called user in a domain called domain.microsoft.com, type:
runas /user:user@domain.microsoft.com “notepad my_file.txt”
When prompted, type the account password.
To start an instance of a command prompt window, saved MMC console, Control Panel item, or program that will administer a server in another forest, type:
runas /netonly /user:domainusername “command”
domainusername must be a user with sufficient permissions to administer the server. When prompted, type the account password.