Recently I have deployed WAAS for just one site, and I am a bit concerned as majority of the traffic falls into "Other Traffic" category. I've discovered this is just a file transfer between XP desktops and a W2003 server.
Why it's categorized as Other?
Correct - that would be SMB traffic. Prior to 4.0.7, it should be classified as part of the File-System application. From 4.0.7 on, it is classified as part of the WAFS application.
Can you please confirm that you have classifiers that cover ports 139 and 445. If so, which application is the classifier associated with?