I think Born2fly has got the right approach. There will probably be heaps of updates, many described as critical or security updates.
My preference would be to stick with WMP10 and see if everything works after the updates. It should. You can "upgrade" to WMP11 if you choose..but it should work with 10 and I would check that first.
I have read on some other forums about some folk being a bit unhappy with 11, from a DRM and complexity of use standpoint.