I recently set up a Win2K server which was going to go WTS and deliberately did not order the CALs (they were specified by the software supplier's list).
I also deliberately turned off the WTS services once the thing was installed to keep them from generating expiration messages (the client didn't expect to apply WTS for some months).
Fortunately, they decided not to go this route, Every once in a while a business person who's using WTS asks me if I know how to make it work right.