slartabartfast
... and a license for XP now is really problematic.
This could be a showstopper. The license registered in XP is linked to the machine ID of your old computer.
XP will recognize that is it not running on the correct machine, and will most likely shut down immediately.
When I replaced the CPU on my old XP computer, I ran into this. The machine ID is tied to the CPU. At the time, XP was actively supported, and moving the license to the "new" machine was easy enough.
I don't know if it's even possible to get a new license for XP at this point in time.
As for VST's, many of the older 32 bit VST's can be bridged.
I kept the original zip files of all of my downloaded VST's on my data drive in the XP machine. That drive is now in an external enclosure($20 from NewEgg), and moving these and project data to my newer computer has been relatively smooth.
And Cakewalk provides links to download a fresh copy of all the VST's I have from them. Does Steinberg offer that as well?
Also, when you load an old project, Sonar will tell you what effects/VST's are missing. You should be able to find something that is currently available to replace the ones that just will not work anymore.