This bothered me for a while in the beta program. But it does kind of make sense.
Apparently you are using the 120-day Eval version... BY default, it is supposed to ignore the setting and show the version on matter what.
If however you are using the cracked version of Win2K with a bogus serial, it is defaulted to off. But once you turn it on, you are stuck with it.
My suggestion... wait till February, and buy it.