I have piles of songs recorded and mixed in Cakewalk Home Studio 2 on my old XP machine, using Cakewalk bundled FX.  I recently built a new DAW machine running Windows 7 and Sonar X1. And I'm trying to open these projects in Sonar X1 and, of course, it doesn't find many of those plug-ins because they're old and some aren't even included in Sonar, apparently. 
 
I'm assuming these bundled plugins are DirectX?  I copied the .dll's from my XP machine 'Shared Plugins' folder I can't seem to be able to simply move the .dll to the 'Shared Plugins' folder on the Win 7 machine for Sonar and get Sonar to see them so I can use them again.  I really like FXPad, for instance and I know of no alternative in Sonar's bundled FX for it.  
 
Is there any way to use Cakewalk FX from HS 2 in Sonar X1?  

Not just DX format, many are 32bit DX plug-ins and will only run in a 32bit DX Host. They were never ported to 64bit.
You will need to install the 32bit version of X1 (I believe the old DX plug-ins will install with it) to load the old projects intact.
 
BTW, copying DX dlls is not enough. Assuming the dlls are for the correct platform (32  or 64bit) they must be registered for a host to find them. Registering dlls uses the Windows command line utility regsvr32.exe.
 
FXPad is 32bit only but SpectraFX is 32 and 64bit version.

Ah, thanks scook.  I did the registering thing, but I just didn't even think about the differences in 32 and 64 bit.
 
I will try to install a 32 bit version of X1, I guess.  I'm assuming registering dll's are so you can move them around and the registry keeps track of them or something?  Thought that was a weird step..I'd never done that before.

Registering w/ regsvr32 writes the path of the plug-in into the registry. Moving plug-ins without re-registering will not work. While they may be anywhere and the host will find and use them, I would unregister the plug-ins with regsvr32 and move them to a more appropriate location. But before re-installing them, see if the plug-ins you want are available in the 32 install of X1. After performing a regular install of 32bit X1, check the advanced install for plug-ins not normally installed. Once you have confirmed plug-ins are missing then add the old versions.

make sure to apply the X1c and X1d updates.

scook
After performing a regular install of 32bit X1, check the advanced install for plug-ins not normally installed. Once you have confirmed plug-ins are missing then add the old versions.

Well...I installed the 32 bit X1 version and both patches C & D and all the old plugins are now in my list of available Cakewalk Fx...except for FXPad, the one I registered earlier.  I tried to register it again, and rebooted, and it said successful, but still no joy. I've tried unregistering and it errors out with an error code 0x80070005, something about the .dll loaded but the call to DLLUnregisterServer failed.  So I'm going to go look that up and see what's going on..
 
Do I need to be careful about saving projects with the two different versions of X1 now on this machine, or is it just a matter of what plugins are available to use?  

Personally, I would try to install plug-ins manually. I would use the installers for the DAW which included the plug-in. Changes are there is a custom install option to pick what to install.
 
Make sure to run regsvr32 as administrator.
 
Take a look at SpectraFX, IIRC it was the replacement for FXPad and is a 32 and 64bit DX plug-in.
 

Voda La Void
Do I need to be careful about saving projects with the two different versions of X1 now on this machine, or is it just a matter of what plugins are available to use?  

Not really. Other than the 32bit DX plug-ins and the memory limit imposed on 32bit programs (which may not be an issue), projects should work equally well in either DAW.

scook
Personally, I would try to install plug-ins manually. I would use the installers for the DAW which included the plug-in. Changes are there is a custom install option to pick what to install.
 
Make sure to run regsvr32 as administrator.
 
Take a look at SpectraFX, IIRC it was the replacement for FXPad and is a 32 and 64bit DX plug-in.
 

Voda La Void
Do I need to be careful about saving projects with the two different versions of X1 now on this machine, or is it just a matter of what plugins are available to use?  

Not really. Other than the 32bit DX plug-ins and the memory limit imposed on 32bit programs (which may not be an issue), projects should work equally well in either DAW.

Thanks for your help, scook.  I found FXPad on the Cakewalk site as an isolated install so I just grabbed that, and it's all working good now.  I will still look at SpectraFX though, sounds interesting and it would be nice to have a 64 bit replacement.  
 
It's interesting, I could never find the fxpad.dll in regedt32 doing a Find, no matter what I did to try to register it using the regsvr32 command.  Ran the actual install file, and then checked again in regedt32 and there it was.  I guess you really can't just put the file where you want and register it. Not sure why, but I'll leave that for smart people to worry about.