If you have Windows 7 clients and or Windows Server 2008, another option to explore is WinRM (Windows Remote Management) and WinRS (Windows Remote Shell).
They do need configuring however. I know you've settled on psexec already, I'm just offering additional info. :)
Really quickly you need to execute winrm quickconfig
on the machine that you wish to control. This quickstart command alters a number of settings throughout the system so it's worth investigating if your security policies allow this before you run it.
Once run, you can use WinRS like this:
WinRS -r:Computername ipconfig
You can, if you don't already have permissions on the target system, run the command with other credentials.
WinRS -r:Computername -u:Username -p:Password ipconfig
You can also use PowerShell commands on remote machines configured for remote management. From within Powershell management
Invoke-Command hostname {powershell-command}
or
icm hostname {powershell-command}
If you have the right infrastructure, WinRM and WinRS can replace the need for psexec.
Cheers
Lewis