Open a command prompt with system rights in Vista (and XP)

First of all, download psexec from the Microsoft website.
http://www.microsoft.com/technet/sysinternals/utilities/psexec.mspx
 
 
From and elevated/admin command prompt (cmd.exe, "run as administrator"), run psexec –s cmd.exe

C:\>whoami
peter

C:\>psexec -s cmd.exe

PsExec v1.83 – Execute processes remotely
Copyright (C) 2001-2007 Mark Russinovich
Sysinternals – www.sysinternals.com

Microsoft Windows [Version 6.0.6000]
Copyright (c) 2006 Microsoft Corporation.  All rights reserved.

C:\Windows\system32>whoami
nt authority\system

C:\Windows\system32>exit
cmd.exe exited on LAPTOP1 with error code 0.

C:\>
 

Type ‘exit’ to exit the "system" command prompt.
You can launch any other tool from that prompt, and it will inherit your system rights