If you use VMLite, you can install the OEM XP on the same host, and your VM don't need to be activated. VMLite preserves hardware info, i.e., it inherits the host hardware, so if your OEM XP runs well on the host, you can create a vm using the same CD, and runs well without activation.
To the best of my knowledge, VMLite is the only virtual machine capable of doing that.