While most here probably use cgminer I am still using cpuminer and batch files, very happy with the performance.  I did test cgminer out and it would only show around 20 of 30 gridseeds.
I have all of them clocked at 850Mhz and they will stay running for days without any issue, running 30 on WinXP host, 10 devices per 10 port Rosewill 10port usb hub.  I get a consistent 10.5-11 Mh/sec out of them.