Otherwise why do I have the registry key HKEY_CURRENT_USER\Windows 3.1 Migration Status on my Clean XP SP2 box?? I later found that others  have also found this earlier and were equally puzzled.

Check any XP machine and you'll see this key. The burden of backward compatibility on Microsoft products is often too great :).  Interesting to note that my Vista box doesn't have it. So I guess Windows 3.1 can finally RIP.

I found it as I was moving through the registry using PowerShell. Manipulating the registry has become extremely simple using PowerShell. You can move into the registry using something like cd HKCU: and then do a dir to see all the keys!! To find the above key try the following sequence.

C:\>cd HKCU:
HKCU:\>dir | select-string "3.1"