Dreambox, comes to mind as a m8 has one and says it's good, I just use freeview and anything her indoors wants is on bbc Iplayer.
Dreambox - Wikipedia, the free encyclopedia
dreamboxshop.co.uk
Have a look and see if they're any good for what you want.
But as mentioned before a freesat or now TV box is a good alternative. (can you not get a free card for the existing Sky box? You used to for about a tenner)
One good trick is tell Sky you're thinking of leaving, they offer you deals to get you to stay
I watch a lot of movies but stream them from the PC onto the Xbox/TV.