I have 2 5850, I achieve 320-330 KH/s each with the following settings:

--intensity 16
--gpu-threads 1
--shaders 1440 <- tune this according to your gpu shaders
-g 2
--thread-concurrency 5600

Last Catalyst beta (13.5 if i remember well), win7 32bit.
The two cards stay at 85/75 degrees... a bit high, but I want to squeeze them as much as possible, since I bought them used for just 70euros  

Tuned with this nice guide: http://zx896.ru/publ/bitcoin/faq_cgminer_for_litecoin/12-1-0-43