Ok, don't laugh but I am still using Cakewalk Home Studio II from way, way back on a machine that runs Windows XP.  And yeah, I'm finally at the point where I am ready to upgrade to Sonar, with a new computer build in the next few months.
 
My concern is how Sonar is going to handle all of my project files from Home Studio II.  I've got over 10 records worth of material, about 20 years of fanatic recording, and I would like to think I could just copy over my project files and the gigantic audio folder and Sonar would open them without a problem....
 
Is that just a silly dream?  

It should be no problem.
Cakewalk changed file extensions about a decade ago, for instance what was a .wrk is now a .cwp, .bun is now .cwb.
I had no trouble opening the older projects in the new programs, but saving them in the new format will prevent them from being opened in the old program. Not a problem for most folks; you already have them on the old computer.
The old projects could have references to plug-ins and synths and hardware which the new computer doesn't have, but all you'll get (probably) is a message telling you just that.
 

Hi. I have the same experience as Greg.
I open projects from way back made in Cakewalk Pro Audio 9, or SONAR 2 and 4 in SONAR Platinum from time to time with no other issues than missing plugin dialog. 
All the best.

They will open, wrk files from back to 1999 for me still open fine.

One thing you will want to consider after an upgrade is using per project audio folders, opening up each project file, then saving as a new name to a new folder for each song. Remembering those days, your global audio folder is probably massive and unorganized.

Doing the above is a slow process, but allows SONAR to copy only the project audio to the new folder that the project file requires. Going forward this would occur automatically so long as you enter a name when creating a new project.

mettelus
They will open, wrk files from back to 1999 for me still open fine.

One thing you will want to consider after an upgrade is using per project audio folders, opening up each project file, then saving as a new name to a new folder for each song. Remembering those days, your global audio folder is probably massive and unorganized.

Doing the above is a slow process, but allows SONAR to copy only the project audio to the new folder that the project file requires. Going forward this would occur automatically so long as you enter a name when creating a new project.

^^ I think this is very good advice  

If at all else fails. 
There's always a way to use old material. 
Are these old projects mostly MIDI? 
If so and if you still can run HS II then save all those old projects as midi files. Those will open on any DAW> I still am opening 1986 midi files made on an Atari in Sonar. 
And if they are audio that's even easier as no big deal to import audio. 
 
SO you can open the MIDI file and then drag the audio to the project and there you go. But hopefully the old projects open without much adieu. 

Thanks everybody, sounds like it's probably going to be no big deal then.  
 

mettelus
One thing you will want to consider after an upgrade is using per project audio folders, opening up each project file, then saving as a new name to a new folder for each song. Remembering those days, your global audio folder is probably massive and unorganized.

Doing the above is a slow process, but allows SONAR to copy only the project audio to the new folder that the project file requires. Going forward this would occur automatically so long as you enter a name when creating a new project.

Yeah, slow process for sure.  I will definitely do this though.  I've taken that global audio folder for granted - just tuned it right out of my mind.