Hyper-V Program Manager
The next game in the X-COM series is 'X-COM: Terror from the deep'. This game is the direct sequel to UFO - Enemy unknown - and uses the same game engine (with a few minor tweaks). The result is that it behaves largely like UFO - Enemy Unknown when run under Virtual PC (i.e. Runs fine - but needs to be slowed down).
X-COM: Terror from the deep is pretty much identical to UFO - Enemy unknown, except that you are battling marine aliens rather than Terran ones. The result is that it tends to feel like 'more of the same' - however there are a number of small UI and AI tweaks that do make it a worthwhile play still.
One trick that I have found is that on faster machines it can be quite hard do 'spin the globe' using the widgets provided (as the globe spins too quickly). This can be worked around by clicking on the globe with the right mouse button - and it will spin to exactly the spot you clicked on.