Change a computers GUID

I'm working in a school who have recently updated to Windows 7 and purchased a whole batch of new laptops. While everything else works swimmingly, there are 6 laptops that appear to have the same BIOS GUID as some other laptops that have already been configured. This presents a problem because the deployment software that we use relies highly on GUIDs, and therefore all hell breaks loose when I try to deploy Windows (and if I bodge the Windows install, application deployment will have the same issue anyway!).

I contacted the manufacturer of the laptops, HP, however as they were purchased a little while before our update plan fell in to place the warranty has since expired.

I've heard that some manufactures supply a script to change the BIOS GUID and serial number, or they have some utility to do it with, but I haven't been able to locate anything. I asked HP for such a utility and the guy I spoke with drew a blank, and then proceeded to inform me that their 'IT Guy' told them the problem is with our Windows image. And that we should use the image provided by HP.. seriously? HP is clearly focussed on the home market with this kind of support.

So all this brings me to a point; Does anyone know of a script that can do this? Or can give me some sort of stepping stone with C or VB?