I read somewhere that the format that the files are saved onto the Sky+ harddrive, is not recognisably by a PC. Nobody has come up with anything (Apart from Sky themselves) which can decode it.

If you want to put them on the PC, get yourself the right cables, and stick your SCART output from SKY into the back of your PC. And get some PVR software to record them into MPEG, DivX, or whatever you want.

It won't be quick (Realtime, obviously). But, that's the only way to get them watchable on PC

However, on another note, it is entirely possible for you to fit a bigger harddrive into your Sky+ box.