So you installed the Windows 7 Release Candidate and you’ve been happily running it and have it configured exactly like you want it. You can keep using it until March 2010 (or June if you’re patient enough to put up with the shutdowns every two hours that will start in March), but sooner or later, you’ll have to give it up and go with the final code. You can, of course, just start over from scratch and rebuild your empire manually. There’s a certain satisfaction in doing that – but these days, many of us just don’t have a lot of extra time on our hands, and we would really like to have a way to preserve some or all of the configuration tweaking we’ve done.

There are two ways, one of which is officially supported by Microsoft and one of which isn’t. I’ve tried both, on two different Win7 RC machines. I described my experience with the Easy Transfer utility in an August post to the Amazon End User blog. This is the method that Microsoft recommends. You create a .MIG file that holds user data and information about your OS and application settings, do a clean install and then restore the information from the .MIG file. It’s pretty straightforward but it has some drawbacks. It takes quite a bit of time to run the Easy Transfer wizard on the old installation, install the new instance of the OS, install all your applications again and restore all the settings. I also ended up with a corrupted Outlook profile, which may or may not be attributable to the Easy Transfer process. Creating a new profile fixed the problem, but it was a bit of an annoyance.

So when I decided to take my Dell XPS from RC to RTM, I thought I’d try the unsupported method. Now, realize that if you go this route, you’re on your own when it comes to troubleshooting problems you have with your new Win7 installation. Since I’m not one who ever calls tech support anyway, that wasn’t an issue for me. I figured the worst that could happen was that it wouldn’t work, and then I’d just wipe it and do a clean install and start over. This method is a true upgrade, which not only preserves your data and settings (without having to take time to restore them) but also keeps your applications intact so you don’t have to reinstall them. If you have lots and lots of apps, or some for which you’ve lost the product keys, this method might be worth a try.

Because Microsoft doesn’t want you to upgrade the RC code, the Windows 7 installer detects when you’re running it and doesn’t give you the option to do an upgrade installation (you can do an upgrade if it detects that you’re running Vista SP1 or above). The trick is to fix that prohibition. To do that, you have to first extract the Windows 7 RTM ISO file to a folder. Then follow these steps:

1. Navigate to the sources folder.

2. Find the file called cversion.ini.

3. Open it in Notepad.

4. Under [HostBuild], change MinClient=7233 to MinClient=7000

5. Save the file.

6. Create an ISO file and run setup.exe

You will now have the option to do an upgrade installation. Select this option. I started the upgrade installation and then went off to do some chores. When I came back a couple of hours later, it was at the point where it asks for the product key. I entered the RTM key and it quickly proceeded through the final stage. I had a tiny scare when, at the end of the installation (after the “preparing your desktop” message), I got a black screen with the mouse pointer fully moveable, but no desktop. I rebooted, logged on, and my desktop loaded normally. My wallpaper, icons, gadgets, etc. were all in place. All of my applications worked flawlessly, including Outlook. I’ve been using it now for a couple of days and have encountered no problems.

I can’t promise that the RC to RTM upgrade will go this smoothly for everyone. Again, I stress that it’s a non-supported method. But it seems to have worked like a dream for me, and saved me a good bit of time. For step by step instructions and screenshots on using this method, see

http://www.intowindows.com/how-to-upgrade-windows-7-rc-to-rtm/