moving to nopcommerce is an excellent choice, but I think your stuck regarding hosting , previous versions of nopcommerce used asp.net 3.5 sp1 - currently it uses asp.net 4.0
It would be well worth your while moving hosts, especially if your current host is sooo far behind technologically - it actually costs them nothing to provide the framework so it says a lot about their commitment to their customers if they can't be bothered providing it ( they are over 2 years behind in whet they provide )
you can find cheap and effective hosting for nopcommerce from as little as $3.50 per month - I'm in the uk also but i use an american registered company for hosting with more than satisfactory results