So another revelation that works wonders ..... with hardware mpeg2 encoding on the TV card it is bit of a shame to then chew 80% cpu trying to watch the stream.
Solution install nvidia binary (evil, evil, evil) video drivers. It appears as though almost all recent nvidia cards accelerate mpeg2 video (http://en.wikipedia.org/wiki/XvMC) with nvidias driver, now I can record and watch video at the same time and only use 5% cpu (about as much as listening to mp3s). Mark
