I'm a licensed user of an older version of Sonar. My computer crashed and I no longer have my installation CDs for Sonar 3.  I talked to Cakewalk and they can't replace my Sonar 3 CDs and they are only able to offer to upgrade me to the latest version X1 or X2. The oldest version of Sonar I found on ebay is 8.5.  I played with newer versions like 8.5 and X1, but since I've been working on Sonar 3 since 2004, I don't have time for the learning curve associated with learning a newer version at this time.  If anybody has installation CDs for Sonar 3 they are willing to sell, please let me know. Sarta53 at gmail.

If this type of post is prohibited, I apologize but please know I have no alternatives unless you can let me know where to find sonar 3 because ebay is not an option and I don't want to go looking thru underground crack world.

I never had version 3, but in the jump from 4 PE to 8.5 PE there was actually no learning curve at all, IMO. The UI is very similar, and the new things that you don't need, you can leave unused, and study them little by little. The basic workflow remained the same. as far as I can recall. It's X-series that radically changed everything.

sarta53, you are not going to find a legal copy of SONAR 3. Your best bet is to grab that 8.5 you found on eBay pronto, because legal pre-X1 versions are getting very hard to find. 

The learning curve won't be too bad at all and 8.5 should open all your S3 projects. You might lose a couple of the bundled effects, although the main ones (e.g. Sontius suite) will still be there and some of the others can be downloaded from CW.