I bought this not knowing what type of recordings I would get, I only use it from SKY to record documentaries through the SCART etc, I used a Pentium 1.5 GHZ at first, with 2 GB ram, but this was not powerful enough, you need a 64bit x2 min with 4GB Ram for good results, don't bother with anything less. It will tune TV through your Ariel, but don't bother with the supplied Ariel, it's crap. If you use your TV Ariel, then you can download the program guide for your channels in windows media centre. I have not used the HD facility yet, but in time I will, also I record in WMA mode as I watch TV through my PC, much better than a TV.
I think this product is worth the money, but in time it will be surpassed by new technology. Hope this helps