Another good option that I have used several times is "OpenConf" http://www.openconf.com/editions/. The "community edition" is free and works pretty well.
'Easychair' is fantastic and very easy to use. http://www.easychair.org/ This is a free facility and is well tested and used by many academics. Hope it will do just what you require.
easychair is good for paper management -- widely used by many conferences. Just register your conference name and details, and you are on. But you wont get things like registraton, scheduling, etc (I think). For that you can use OCS.