Thank you all for your ideas and suggestions. I'll give them all some thought.
To be honest, I don't really want to go to the trouble of installing a dual-boot system, or a virtual machine, or even Sandboxie (but thanks for telling me about that program, Vroo; it looks like it is worth knowing about). I might find it easier just to use a second laptop.
Susan, I like your idea of using the Mobipocket Reader, although it would be a bit drastic to have to remove all the DRM. I'm not sure if I feel comfortable with the ethics of that, plus Mobipocket Reader wouldn't give the advantages of syncing with the Kindles that the Amazon program does. However, it's defintely worth considering.
I'll experiment with some of these ideas, and let you know which one I eventually go for.