Thanks, in advance, to all who comment. A little background information. I'm presently running Windows XP via Parallels on an external drive via FW800. It actually runs quite well. This setup works brilliantly for Windows software, Altium. The magic mouse top scrolling is great. It setup works better that what I have done on a pure Windows machine. Now the rub. It's time to move on. My iMac is 2009 vintage. XP is now obsolete. Time to move to Windows 7 or possibly 10. I have a mid 2014 13" MBP too. Its great, but for screen size. So I'm looking at upgrading to a new iMac or perhaps a new 15" MBP. If I buy an iMac, I'll want to run Windows on it. If I buy a MBP , I'd prefer not to use partition the SSD. Has any one run Windows on a fast USB thumb drive? Or on a fast SD card? If I go with an iMac, I'd like to run the same windows on my 13" MBP. Hence the thug drive/sd card idea. What works well?