As those that follow know, I briefly lived in the W7 Professional world in order to test out Microsoft Virtual PC.  I have found that, at least for my needs, VirtualBox is a much better solution.  I also found out that VirtualBox will die the moment Virtual PC is opened, so Virtual PC had to go.  With it gone, there was no need for Professional anymore, so I started the quest to downgrade.

Many a forum post will tell you its not possible.  Hogwash.  Yeah, its not exactly supported, but presuming you have a legal copy of Windows 7 Home Edition, and a valid product key, its doable.  You just need to insert the DVD and run an upgrade.  OK, OK… its not quite that simple, but close.  If you try and run the upgrade, it will complain that downgrading isn’t doable.  If you do the registry hacks to make your Professional Install look like Home Edition, it will get farther, but die from a message similar to “Installed version is more current”.

The trick (yes… there is always a trick isn’t there?) is to use the Microsoft Compatibility settings to trick the setup DVD into thinking your running Vista.  Its really that easy.  Just install the DVD, but don’t start it.  Open it.  Highlight “setup”, then tell Windows to run it in Vista SP 2 Compatibility mode.  Works like a charm.

Downside?  It takes FOREVER!  I’m talking like 12 hours on my machine.  But it worked.  I’m beginning to understand why my Windows Engineer colleagues hated to do upgrades and always preferred a fresh install.  During my “upgrade” over 800,000 files and settings were apparently ‘saved’ and later ‘restored’.

Of course, a fresh install is always an option (and is much, MUCH, quicker), but then you lose all your files and personal settings.  Personally, I store most of my files elsewhere, but “personal settings” include things like game data, Thunderbird account settings, etc.  Those e-mail settings will a killer since I use Thunderbird to consolidate a good half-dozen e-mail accounts.