If you purchased Office 2010 and want to use Outlook to send mail from other applications (like QuickBooks), use add-ins or sync with a smartphone, you do not want the click-to-run installation. 

Click-to-Run installs in a virtual space. This is great because it allows you to have two Outlook’s installed and want to try Office 2010 but add-ins and sync software won’t work with it. 

If you installed Office 2010 Click-to-Run and it does not meet your needs, you can uninstall It and install Office 2010 by using a method other than Click-to-Run. To do this, follow these steps:

  • Uninstall the Click-to-Run version of Office 2010 from Control Panel.
  • Visit the site where you purchased Office 2010, and sign in with the same Live ID that you used when you first purchased Office 2010.
  • Click the My Account link at the top of the home page to access your Office downloads.
  • Click the Download button for the suite that you purchased, and then click the Advanced Options link under the Download Now button. There is a version of Office 2010 listed that is not Click-to-Run and that does not require an available Q: drive.

Office 2010 Click-to-Run compatibility with add-ins
http://support.microsoft.com/kb/982431