I'm a noob miner.  What value should I set CGminer's "-w" at?  It seems to default to 64 - is that ok?  It's a lot higher than others and I get 20k h/s less than at xpool.  My command line:

one HD6870:
 --scrypt --expiry 1 --queue 0 -I 18 -g 1 -s 1 --gpu-platform 0 -d 0 -v 1 --thread-concurrency 6720 -o http://dgc.cryptocoinmine.com:7070 -u worker -p password

and woohoo, my pool user id is 2