I have purchased a downloadable version of Premiere Elements 10. At that time I believe that there was only a 32 bit version available. Now I found there is a 64 bit version for win 7 64 bit. Can I download and install this version over my current version with the existing serial number without losing my data ?
Remove the old version before you install the new. You won't lose any data or works in progress when you uninstall the program.
Also, from the Adobe download site, be sure to also download and install the Additional Functional Content. It is a separate download and install, than the program.