Very helpful thread, thanks. On 2008 R2 SP1 I tried the environment variable (with migwiz copied from Windows 7) and had no joy, but halladayrules’ Application Verifier approach worked fine. [Update: yes, but I still can’t get migwiz.exe to do anything useful. See below].
For 2008 R2 SP1 my system showed 7601 as the build number so I used that value in Application Verifier (I didn’t bother to check whether it might have worked even with 7600).
Good news, bad news (mostly bad): yes, the Application Verifier approach allows migwiz.exe to start up, display its wizardly UI, etc. However, there’s something weird going on that renders it pretty much useless. From the moment it starts up it’s using 100-200 MB (OK, fine), but from then on it starts chewing up more and more memory (even if you’re just sitting there on the initial UI screen). Just for grins I let it run for a little while and it blimped up past 4 GB and showed no signs of stopping (I could see my system growing pagefile.sys). I tried migwiz copied from a couple of different Windows 7 systems and got the same results.
I don’t know whether this is a general problem with running migwiz on 2008 R2 SP1 or whether it’s somehow peculiar to my system (an old Dell Latitude E6500, although I doubt that’s significant). In any case, I think I’m going to file this one under “Wizards are great when they work just right; when they don’t, you’re probably better off without them”.