Lars,
HTPC is short for Home Theater Personal Computer. The biggest advantage of a HTPC is you can custom design many different output resolutions to tailor specifically to your display device. For DVD playback you would be hard pressed (read:impossible) to get a better image spending the amount of money on a scaler that you would on a HTPC. It wins the bang for the buck race all day long. That said, I use my filter modified Quadscan most of the time, go figure.
Adam