The other problem with this - unless I'm missing something - is that you can't just image your hard drive and expect it to work on a new computer because the Windows installation on the disk image will not activate on a new machine. Linux, on a free distro, would be another story - just take the drive out of your old computer, pop it into the new one, and boot up. Except you would be limited to the free version of Hauptwerk v4 (running via Wine).
If you are going the route of casting V4 in stone, it might make sense to buy the new computer now. If you are old like me, that would take care of the problem.
However, V5 would be cheaper!