We do run on 2008 HPC, but only if you don't install the Cluster pack. Essentially, only install the Server operating system, and then the qube core and worker components.
In this mode, the Server HPC nodes are similar to any other Windows Server OS version, except that the OS starts up ~much~ faster and has less of a resource footprint.
We've also noticed that our Qube 6.0 msi installers are having some issues with the permsisions on Windows 7 / Vista / 2008.
The recommended install procedure for these OS's is to uninstall any previous versions of Qube, along with the GUI, supervisor, and worker, and then open a command prompt with "elevated privileges" (Microsoft's term). From this "privileged" command promp, perform the install with the msiexec utility:
msiexec /i <path_to_msi_file>
Do this for each of the Qube components that you need to install on the machine in question.