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marked as duplicate by nhinkle Jun 28 '11 at 1:16

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

The 32-bit and 64-bit Windows FAQ states:

If you want to move from a 32-bit version of Windows to a 64-bit version of Windows Vista or vice versa, you'll need to back up your files and then choose the Custom option during Windows Vista installation. Then, you'll need to restore your files and reinstall your programs.

Thus make a back-up if you want to and then reinstall, there is no other feasible way...

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The 32bit to 64bit conversion makes fundamental changes to the way your system runs that can't be done on a running system. You will have to re-install windows and everything that goes along with that.

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As a rule, switching from 32 bit to 64 bit, or vise versa, cannot be done as an in-place upgrade. Even if it's the same operating system. You need to back up your files and programs and do the whole install.

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