These are the steps I've been using to gpu mine on windows:
1) Download modified cgminer scrypt: https://www.dropbox.com/s/ksgtrltpah1eqes/Vertcoin-CGMinerAleksNR3.zip
2) Use notepad++ to create a .txt file, then convert extension to .bat file.
This is the code I've been using for dual x280's:
setx GPU_MAX_ALLOC_PERCENT 200
cgminer.exe --scrypt -o stratum+tcp://us.bitcrush.info:3444 -u Weblogin.Worker -p Worker password -I 12 -v 1 -w 256 --thread-concurrency 8191
This is the code I've been using for dual 6950's:
setx GPU_MAX_ALLOC_PERCENT 100
cgminer.exe --scrypt -o stratum+tcp://us.bitcrush.info:3444 -u Weblogin.Worker -p Worker password -I 12 -v 1 -w 256 --thread-concurrency 4096
*any higher TC or intensity>12 seem to give errors
3) Run created .bat file
x280 = 275-350 kH/s
6950 = 125-175 kH/s
Goodluck