[zenexer]

I don't think you're going to be able to go the virtualization route with Windows 2000 as the host. As the client, sure, but not as the host. You'd need at least XP.

For many contractors, Windows 2000 as a requirement would be a red flag--decline the contract and run the other way, because that's just where it starts. Chances are you're looking at the tip of the iceberg.

Since you're already committed, though, your focus should probably be on pushing them to upgrade whatever they can. It's a lot easier to run old software on new platforms than the other way around. Whatever ancient programs they want to run, they can do it on newer versions of Windows--there's guaranteed to be a way, and it'll be a lot easier than getting a modern application running on Windows 2000. Lots of people want to run old programs on new computers. Nobody wants to run new programs on old computers.

Edit: To clarify, there are great programs like DOSBox that will let you run old programs you wouldn't normally be able to run on new versions of Windows. DOSBox targets a specific niche, but it works well, and the concept is quite prevalent: people want a way to run their old programs, even if it's just for nostalgia. I would bet my life on it being significantly easier to run their specialized software on a newer version of Windows, even if it's in a VM. (Or, heck, what about WINE, since they have Ubuntu?)