Has anyone got one of the above, and been able to get the microphone
working ? (the odds are several other machines use the same chipset)

The chipset appears to be the STAC92xx - playback is fine (but only from
the front headphone socket), just the microphone doesn't work - pretty
much every sound capture test in sound prefs results in this error:

Failed to construct test pipeline for 'gconfaudiosrc ! audioconvert !
audioresample ! gconfaudiosink profile=chat'

While i'm at it, if anyone knows how I can enable the rear outputs as
well, it'd be appreciated :-}