- There is no migration path from 32-bit to 64-bit Windows
Microsoft do not provide a migration tool to take your installed software with you when you move from a 32-bit version of Windows to a 64-bit version. When you make that move you are expected to re-install all your programs from scratch. This is unlike, say, an upgrade from Windows Vista 32-bit to Windows 7 32-bit where you have the option of doing an in-place upgrade.
This isn't a case of Microsoft being mean or lazy; there are very good reasons for it. A lot of software will install different (or additional) components, in different places, with different registry settings when on 64-bit Windows. Any tool which naively attempts to move software components and registry settings from a 32-bit machine to a 64-bit machine is not going to know about those differences, especially not for every piece of software you may have installed. Even if it did somehow know, it would not be able to obtain the extra components required on 64-bit versions of Windows.
- Third-party 32/64-bit migration tools
Some third-party software vendors have attempted to make tools to migrate your programs from 32-bit to 64-bit Windows. We strongly advise against using these migration tools because they are likely to cause more problems than they solve. There are very good reasons (outlined above) that Microsoft don't provide such a tool themselves.
As well as leaving your software in a state where parts of it may not work, such 32/64-bit migration tools may also break installers and uninstallers, leaving you unable to update, repair or remove some of your software. This is because the software's components and registry settings will be in "impossible" combinations and places which the installers themselves would never have created on a 64-bit machine.
- Fixing Directory Opus if you have used such a tool
GPSoftware have created a special uninstall program designed to clean up the mess created by 32/64-bit migration tools. If you have run such a tool you should run this special uninstaller and then install the 64-bit version of Directory Opus.
This will only fix Directory Opus, not all your other software. You should still consider reinstalling Windows to avoid problems with your other software. If you don't, you won't know if any problems you experience down the line are due to incorrectly migrated software or something else. Reinstalling now, getting it over and done with, may save you time in the long run, but it's your computer and your choice.