will have a look at the advanced setups and usage page, thanks. i had actually just come back here to post that i was 100% that it was working --- as i found an inbuilt benchmark of sorts, the glxspheres64 command. running it as default i'm getting FPS in the mid to late sixties, running optirun glxspheres64 however gets me just shy of 130fps. very nice!
all that being said, i haven't yet had any luck getting any steam games to run with it .. but i'm definitely making forward steps.
again, thank you for all your help and patience, i feel a bit like someone who hysterically calls up IT helpdesk and has their lifethreatening problems solved by being told 'try turning it off and then on again.'