I recieved all parts on Friday, and built the machine on saturday. After 4 hours of methodical PC building - all has come together. Audio passthrough is working, power on / off via remote is also working well.
As far as the hardware goes, no issues so far.
I've configured the system with the latest drivers for all hardware. MediaPortal is updating the LCD display properly, audio is working like a dream - and the HVR 2200 is configured and working well. EPG is also coming out fine via an automated process.
So - as far as the build goes so far, all is good.
Thanks go out to everyone so far for your advice and help. It's made this process so much easier. :)
At some point I'll get some photo's up.