Sinner_G - 3:44 pm on Jul 11, 2002 (gmt 0) <added> and btw, welcome to WMW (finally got to write that :) )
If you can change your client's pages, I would add a cookie or a session ID, which would follow users from their entry page (including referrer and search phrase) to the conversion page. At that point, the cookie info could then be saved with the sale data. Then you just have to compare that to your webtrends stats.
<added> and btw, welcome to WMW (finally got to write that :) )