There is no need to uninstall your current Office installation first. MSI-based installation Now that your computer has been prepared, you can run the installer to install Office By default, it will install the bit edition unless you specifically tell it not to. If the bit edition is what you want again; this is recommendedthen just follow the setup instructions and move to the next section in this guide. If any such application is still installed, you will not how much is Outlook 2015 for subscription? able to install the bit edition of Office. To install the bit edition, you must close the current Setup window and browse to the installation source for instance on the CD or DVD-drive. Open it and run the setup The setup process is further the same as for the bit version of Office. Starting Outlook for the first time after the upgrade When you start Outlook for the first time after the upgrade, the startup could take some time. This is because how much is Outlook 2015 for subscription? previous settings are being migrated. Mail profiles are upgraded on startup and some accounts will be re-cached. If you are upgrading from a version earlier than Outlook Service Pack 2, then several extensive file structure changes to the pst-file are being made which could take a lot of time especially with a large pst-file.