Windows 7 has already earned itself a blue ribbon, and it isn’t even in stores yet.
Microsoft has released a chart to help users figure out what upgrade paths are open to them.
Also realize that you’re free to’t mix architectures if you want to upgrade without a clean install.

There are a couple more things worth noting here.
This approach might take more work than just installing fresh, and results will surely vary.
If anything, ensure to backup any precious data before having a go at it.
Did you know?If you’re ‘stuck’ without an upgrade path, don’t fret.