Download Link Removed - Invalid URL (a portable app.) and click the "Additional Tasks" to:- Clear old version and useless JRE files, remove the autorun /start up entry and remove the auto updater.
Seeing as how you may have some of v20 on there it might just pull all the v19 files and registry entries out of the system..
It is always best practice to un-install Java before installing newer version. Also note the current version is 6 update 22