[cityboy]

What you need is a smart splitter that will split the single dish feed into two signals and then you connect one to each LNB port on the Sky+ (or HD) box. The "smart" bit of the splitter is that it gives priority to one LNB - connect that one to the second LNB port (which is the one the recorder uses unless you are watching the programme you want to record). That way, you are guaranteed that your chosen programme will record. If you are watching another channel at the time you can carry on doing so unless it is the opposite polarisation to the one you are recording. So, this is not as good as two LNB feeds but much better than just one.