It might be because you're using vmware, then. I used Microsoft's own virtual environment.
After a bit more digging - it is. If you're running Win7 pro, enterprise or ultimate and your PC is up to the job, you can
install a virtual copy of XP.
There needs to be "hardware assistance" but you can check for that at the above link. If your machine is younger than 10 years old, it's probably got what it needs.