The mac powerbook G4 is an extremely powerful and sophisticated tool. These notebooks are bought to do specific tasks and to do them well. If you thought that most windows software would work on the machine then you have been ill advised.
As to virtual p.c. This will bring windows down to crawl when you run the emulation.
and at about £200 it ain't cheap.
Try and think what you want the machine to do. Macromedia Dreamweaver is compatibile with MAc click here click here
As are office aplications that can work with windows on other machines click here