Does anyone know if Sonar 8.5.33 can join two avi's and render them without quality loss?
 
Thanks - rev

No.  Sonar 8.53 has very basic abilities to view a single video file  at a time.  There are no video editing  or joining.functions.  There are tons of free programs that can do what you want:
 
http://www.techradar.com/us/news/software/applications/best-free-video-editing-software-9-top-programs-you-should-download-1136264
 
 
moviemaker is the simpolest to get your hands on and probably simplest to use, although I doubt there are any lossless output options (have not used it recently to say for sure).
 
Lightworks is by far the most powerful and is truly a pro level editor, having been used to edit many blockbuster movies. 

Hey Rev.
As Dub mentioned, the video file imported into Sonar must be a single, contiguous file.
There are no video editing capabilities in Sonar whatsoever. The video function is mainly to give you a reference for synchronizing your musical score.
Moviemaker will do what you want, and you already have it. It can export avi, and should give a bit-for-bit render.
You can't get too crazy with it, but it will perform basic edits.
Remember, avi files are very large, and uncompressed, so allow plenty of space on your HD.