That depends on what your trying to emulate.
The new (intel) Mac Minis can not emulate intel (what windows runs on) because they already are intel. Apple has switched the processor type. The old Power PC minis can do it just fine (because the emulaters were created to emulate intel for PPC). That might be why your confused.
Also, macbooks don't "exist" yet. You might be talking about MacBook Pros, which can't emulate (again because they are intel). Or maybe your talking about PowerBooks (which are PPC and can emulate windows.)
If the computer you interested in has PPC processor it can emulate windows using virtual pc or some other program.
If it is an intel, you can install windows natively. Just install bootcamp, available from apple for free, and go.
Hope that clears things up a bit.