Who's running what reports in SSRS 2005

We are trying to see if it's possible to see which users are running what reports.
When users hit a report, they have to enter their WIN credentials.
We do have the default switch is 3:
<!-- 1 = error, 2 = warning, 3 = info, 4 = verbose -->
<add name="DefaultTraceSwitch" value="3" />
...so we're getting the full log, and I see what reports are getting run, but wanted to see if there's a way to see who's running them.
Thanks!

Thanks Yulika!
http://forums.microsoft.com/msdn/ShowPost.aspx?PostID=4095629&SiteID=1