Upgrade: Home Premium to Ultimate 32bit

Hello,

A very quick question:

I recently bought a Compaq with Vista Home Premium SP1 installed in French (I live and work in Paris but am English), and want to change the language to English.

I understand that it is possible to change the language in Vista Ultimate using MUIs from Microsoft.

So, if I buy the Anytime upgrade from Microsoft, I should be able to change the language to whatever I like?

One last question:

Would I buy the French Version of the anytime upgrade (i.e. the same language as is installed) and then change using the English MUI?
OR
Could I buy the English upgrade and install this?

Thanks for your help

Marv