the tuners dont really make a difference what channels are available.
just get any freeview tuner, and u should have access to all freeview channels, as long as your aerial is good enough.
the hauppauge nova-td are pretty good.
theres 2 types, the nova-t and the nova-td, the td has a dual tuner so you can watch and record seperate channels, or join them together to get a better signal from 2 aerials