I posted this on the GPBVR forum also but since I am not sure it's a GBPVR problem I thought I would summarise it here also since might be more NZ users here :)
I will describe the situation in case others might experience this
Have an AGP Sapphire HD 2600XT (had to get the AGP version because of the motherboard). From reading various bits online it seems Sapphire had to hack the drivers to support this video chipset in AGP
With the latest GBPVR, the latest video drivers and the latest Monogram DS filter for TV1/2/3 I can record and playback fine with the CPU (a modest Sempron 3000) running at about 15%. I can also do live TV directly - not delayed playback. This is a huge leap over what I could do before which was basically nothing :)
I am using the latest Catalyst drivers from Sapphire. Can't use the ATI ones since they appear to be for PCIe only which seems to confirm that Sapphire have modified the drivers to work with AGP
PowerDVD8 plays back the TV1/2/3 content fine and with hardware acceleration enabled again the CPU load is minimal. Of course now we are not using Monogram since PDVD8 has its own AAC filters.
But this is the strange thing. Either in GBPVR or in PDVD8 if I try to playback non HD content (576p stuff from C4 TV6/7) the video is corrupted completely and both GBPVR and PDVD8 lock up eventually. Out of interest I turned off hardware acceleration in PDVD8 and it now plays the content fine but CPU is now up to about 80% but still smooth so it's not a huge issue.
I suspect it's a display driver issue. Of course I now do have ways around it. Play HD content in GBPVR and the non HD content in PDVD8 but it's a bit fiddly. Not sure if there is a way to turn off HW acceleration in GBPVR so confirm my suspicions but have asked sub
At least now it's not so critical that either TVNZ get off their butts and broadcast AC3 audio (so I can dispense with the PC to play content and use my Popcorn) or Syabas get their firmware act together and support AAC-HE audio