If you want to stream from source to computer, get something like the WinTV PVR - I have had one now for a few years and it's great. What I tend to do is get the stuff recorded on Sky+ and if it's worth keeping, I encode it onto the pc and archive onto dvd using nero..... the burning to dvd bit takes a night time to complete if it's a full disk.
My parents are currently looking at a freeview hard disk recorder rather than replace the video recorder - it'll be easier for them to whistle through the menu with remote than look for an episode of something on a single video amongst many others which aren't labelled
-Alex