> I'm thinking the problem is that the img src doesnt
> have a file extension and HTTrack is bypassing it
> for some reason.

Extentions are irrevelant like: "<img src=getImage.cgi?id=5>"
The file type from the server is the key. But mime types in 3.4x were broken. 
Try 3.32 <http://forum.httrack.com/readmsg/17840/17833/index.html>