ok got myself up and running - put a dummy plug on the 5770 and got it running straight away. Thought the dummy plugs were only necessary for Windows - maybe you can get away without them on Ubuntu but for the sake of 3 x 22c resistors and one of the plethora of DVI/VGA convertors I have in the parts bin it finished off 4 days of stuffing around quite quickly.

Although when I first ran cgminer I was getting really bad hash rate, dropped the -g to 1 and 5770 worked and 7950 halved, tried to do "-g 2,1" but errored with "2,1 is not an integer". So running two instances of cgminer - maybe this could be fixed in a future release?

Hash rates disappointing compared to cgminer in windows 7 on identical 5770. So going to abandon Ubuntu for now and try windows 7...

Although I do read that I have been asking for trouble mixing 5XXX and 7XXX cards which may not have helped either.