Product ID from WMI

[AndyS]

Is it possible to retrieve the HP product number from WMI? I need this to check warranty status on a number of machines the problem i am having is that I am using:
WIN32_computersystem objitem.model

but depending on the hardware the script is returning the friendly name of some systems, for instance "HP Proliant DL380 G4" which is not valid as a entry on the warranty page.

On desktops the output appears to work and provides the same response i.e. machine model fiendly name but also appears to include the actual product ID ( which means i can trim this to provide the actual product ID for the warranty page)

For server based systems is the product ID stored anywhere else?