I think it means that PyQt4 is either missing or not installed properly. You can get it for your desktop machine from http://www.riverbankcomputing.co.uk/.../pyqt/download.

Im not sure if, by running XP as a virtual machine, how that may effect the installation.

On the n900, you can download it from app manager or it'll come with other applications you install that make use of python. I think gpodder is one of them..