check out www.musita.com its a cost program but it in a pkg format and installs in less than a minute and gives you great bandwidth stats per domain and ip not just ip based.
We have been using musita for about 6 months now. It only monitors the http and nothing else as far as I am aware ( I could be mistaken if they have upgraded recenetly). We did have a couple of problems setting it up, but, the staff at musita are absolutely great. They were extremely helpful and did not bill me until everything was working. Once it was working it has worked great ever since. it offers clean and concise information.
If all you need stats for is for the http traffic then go with musita. If you need full bandwidth monitoring in and out, then I would look elsewhere, as we are doing now.
-- James Riordon SysAdmin http://www.amigo-3.com