For a cheap and cheerful way of extending (what's already on your STBox) into another room, all I did with my setup was:
At the point where the normal TV coax comes out of your VCR (if you've still got one that is) to go into your telly, connect it to the common side of a two way splitter or (better still) a coax switch. Connect one of the other sides (of the splitter/switch) to go back into your telly and the remaining to a coax that runs up to your TV in your bedroom. This way, whatever is on your cable box downstairs you can watch up upstairs.
One note, if you wish to watch cable upstairs don't have your telly on downstairs, if you do you'll lose signal strength and end up with a poor picture.
If you're uncertain on how to do this, PM me and I'll send you a diagram. It's a cheap and easy way and it works.

If I get responses from a few others then I'll put the solution up on the forum.
Si thee