The 650 supports 4 monitors though most only have 3 connections. But yes you can use a 8400gs to run more monitors.
Great, thanks mate. The 3rd port on my 650 is an HDMI and none of my three monitors support that, I figured I could use a host of adapters, but would rather just use the 650 specifically for my two editing monitors.
Thanks again mate, gonna get it all hooked up and ready to go now. ^.^