High outgoing HTTP Traffic

I'm trying to track down the cause of high outgoing HTTP traffic on several of my sites. I really don't know what to look for in Webalizer or AWStats to point me to a problem on the site or if it's just part of the website. If any of these sites have been compromised, I want to make sure that they are fixed ASAP.

What specifically should I look for in the log files and if I find something suspicious, is there any way for me to block that traffic? The sites in question are on Windows Servers.
The best place to start to look for is the number of visits for a particular page on your website in awstas or webalizer. Also check logs to see if there is lot of request from a particular IP. Also please open a ticket with us with the domain name in question and we can also check it out for you and update you as to what might be going on.