Media Center region/country setting on vista ultimate

My media center is set up for the incorrect country - so I cannot search for
online content in the country I am located in! (and if i try and get it from
the country that is set - the provider blocks it because of my IP address!).
I cannot find anywhere that I can change the setting to the correct country.
I have correctly set my location in the Regional and Language settings and
still picks up the incorrect country... any suggestions greatly appreciated!