From: Mr. listman [mailto:savethelist at hotmail dot com] 
> ON the proxy server u can then see exactly whose doing what... I don't
think that u'll also be able to see the exact amount of bandwith 
> being used with the proxy either, u might need to use an add-on, ex. we
use 
> Squid Proxy Server, and ontop of that we have Smart Filter, u can also obt
> for using WebTrends Proxy analyzer or some tool in that catagory to read
the 
> proxy logs, and u'll see exactly whose using how much of the bandwith...

Why pay money for commercial software?  Sarg does a great job
http://sarg.sourceforge.net/sarg.php and is open source.

> If u take the route, u'll either need to mark you pc's with specific names

> or ip addreses, unless u are using MS ISA server, which u can tie into the

> domain, and see exactly whose login name was doing what..

Any decent sysadmin has a log of user/date/time/machinename logins.... Even
if its just 
	echo $user $machine date >> \\server\log\logins.txt

The original poster said that each user has their own machine anyway, so not
such an issue.