Migrating to Win 7 64 - old projects are toast?

I've got a new machine coming next week and am making the transition from XP 32 using 8.5.3 to Win 7 64 and wanted to approach the migration process correctly. 
 
To date, I've not been able to run X1 at all due to crashes on my current system (though 8.5.3 has continued to run fine on it), but hopefully a new state-of-the-art custom DAW from PC Audiolabs will correct that. 
 
One concern I have is the likely inability to open legacy projects - something tells me that compatibility is a pipe dream and that I will still need to run the old system indefinitely to successfully open the 1000+ Sonar 8.5 and earlier projects I have created over the years for production libraries, etc.   Nearly all of these projects contain numerous 32-bit VST plugins.  I haven't worked with jbridge or bitbridge at all, so don't know if it helps in opening up old projects.  I assume that I will need to install both the 32-bit and the 64-bit versions of VSTs in order to have any hope of opening old projects, but just having the old one installed won't accomplish much if I still need to reload them in one of these bridge. 
 
In a perfect world, if the equivalent 64 bit VST was available on the system, projects created using the 32-bit version of the VST would simply point to the 64-bit VST when they were opened, but I can't imagine that being the case here. 
 
So, I'm curious how Sonar handles the opening of files - does every old project just open up with a constant message  about "Plugin not Found" leaving you to figure out what plugin patches and parameter tweaks you made to each and every track and then try to reload them for every track and FX bin and recreate them from scratch?
 
I fear this is going to be the case - no backward compatibility with projects due to the change from 32 to 64.  Am I correct in assuming this?
 

I have projects going back to Pro Audio in the wrk file format and newer. Every one that I have opened in X1 has opened.

What you may run up against are old plugins.  Old DX plugins are not going to port over but they didn't port over in Sonar XX 64 bit anyway. If you need these plugins install 32 bit X1 along side 64 bit X1.

CW has an outstanding record in supporting old projects. X1 can read any old project files as long as they are not corrupted. If you have a good HD system that should not be a problem.

There is supposed to be 100% backward compatibility with ALL Cakewalk products. 

The problem might be that once it is opened in X1 it will not open correctly in the older Sonar. 

here's my experience. 

I started on Cakewalk Pro8 ( preceded Sonar by a number of years and was the top of the line product in it's day) so this software is old. It's highest OS was Windows 95.  I had to upgrade the OS for business software so CWP8 stopped working since it was not supported nor were the audio drives ever updated by the sound card manufacturer.  I didn't record music for a number of years as a result. A number of years later, I bought Music Creator 4 which is a "beginner DAW". 

I was able to open the old CWP8 projects from a CD bundle file.  A majority of the files opened just fine, but several were corrupted and would not open..... Likely from disk problems from setting on the shelf for a number of years. 

Recently I upgraded to X1 and again I am still able to open the old MC projects with no problem and no loss of plugs or anything in them. 

When I attempt to open the projects that I have recorded or edited in X1, with my old MC4, I see a warning pop up that says the project was created in a newer version of Cake and it might not contain all the audio data and other stuff..... O click OK and the pop up goes away and the project opens and runs properly with (seemingly) no loss of anything. 

So have no fear.... old projects will load up just fine. 

since I'm still on 32 bit OS... IDK the answer to that. 

I'm not worried about them being able to open - that usually isn't an issue.  The concern is that the new 64 vs. 32 bit plug-in environment will open these projects in a state that has nothing but disabled/missing plugins across the various tracks and FX Bins (and thus un-playable without a ton of reloading and re-assigning). Sonar generally is not very helpful in this regard - it simply offers to disable the missing plugins so the project can load, leaving you wondering what patches it used, what tweaks had been done to it, what the automation assignments were, etc.
 
In my case, the plugin selection, finding the right sound (the patch selection) and subsequent tweaking represents a huge portion of the work on projects, so even a "simple" swapout of 10 plugins could be a half hour of futzing.

I haven't seen a bunch of posts complaining about this, so maybe it is not an issue.  

In any case, I am going to be diligent about putting the 32 and 64 bit plugin versions in separate areas and hope for the best.

A quick update on this - happily, it appears that old projects are opening fine in both X132 and X164 as long as the 32-bit version of the plugin is installed.  No futzing around needed. 

After my near-year of not being able to use X1 on my old rock-solid 8.5.3 machine, I have to say I'm very happy with the speed and stability of X1 64 on this new machine - can't really get it to break a sweat. 

Now, if I could only get rid of the ghastly light gray clips on slightly lighter gray foreground with a background of medium gray with gray highlights with grayish fonts.  They should have called it G1 for Gray instead of X1.

SONAR X1 is backwards compatible loading projects created in any version of SONAR. This is irrespective of whether the file was authored in the 32 or 64 bit version. That plays no role in the data saved in the project file.
The only caveat is that when loading a project you must have all plugins available. If not the plugin is replaced with a standin. Howevereven then there is no data loss since the plugin data itself is preserved.
Once you resave the project in X1 earlier versions will display a compatibility warning but the actual data is still intact in the new file.