Proxy Server

Greetings,

I have a Vsat internet connection and an ICS network with Windows 2000 server (but I don’t user the active directory- people do not logon to the server). I want to monitor the internet usage and amount of downloads occur by each user.
The only solution I know is to setup a proxy server. Does any one have a better solution. Can someone give me some information how proxy server works, do I need to enter a proxy setting in internet options of each user computer?

Thanks