How should I handle the Dropbox app before and after reinstalling Windows on my computer?

Hey jeroenws, thanks for your post!

You are actually right on the money with the steps here.

You'll basically need to unlink the computer first, by signing out of the Dropbox desktop app and then uninstall it.

After the Windows process is done and you reinstall the Dropbox app, but don't want to re-download all of your files, you need to choose the "Advanced" setup option during the installation process. 

Then you need to choose the parent folder of the existing Dropbox folder as the location for this new install, in your case the D: drive.

If you're connecting with the same Dropbox account, the app will detect the existing folder and will then prompt you to merge the Dropbox folder.

Upon merging, the app will check the existing files locally and the server versions and update accordingly.

Note that conflicts will be created if any changes are made to the files in the Dropbox folder or on the web interface while the folder was "offline".

I hope this helps, but let me know if you have any questions!