I have used a Hauppage USB serial Satellite Reciever and it worked a treat.
It has the advantage that you can record programmes on to your hard disk as well as watching a different channel.
Didn't cost very much something like 60 quid. You can get them with a smart card reader or even use a separate smart card reader so you can get whatever sky channels you are subscribing to as well as the freebie freesat ones.
WinTV 7 software is quite good you can download the database of your chosen satellite's channels from their website so you don't have to waste time scanning for channels you just point at your chosen satellite and go!
Gives you the opportunity to store favourites per user too.