rolling back from v11 to v10

I was hoping to get some advice regarding rolling back from v11 to 10.

My wife got a laptop with vista business installed but was given the option
of rolling back to xp-pro 32 bit sp3. She opted for it because she wanted
everything familiar for now and will probably go back up to vista in the
future.

She would prefer to use wmp v10 and I have read about how to uninstall v11.
It seems straight forward but I have a few questions regardless.

I did not perform the rollback to xp so I don't know if ver 10 is there to
rollback to, and if not, would it just default to v9 or would I end up with
no wmp at all and I can just install v10? Also, I've heard that sp3 doesn't
allow uninstalltion of IE7. This isn't also true of wmp11, is it?

I appreciate any tips and recommendations you may have.