Organizer Install error - compatible NET Framework not installed

Cannot install Trial Organizer files on PC running XP Pro SP3, with updated NET Framework 3.5 and 4.1installed.  Running Outlook 2007, fully updated.  

Error message aborts the install and reads that install cannot be completed, because compatible version of NET Framework is not installed.  

Suggestions how to address this iisue, so that the Organizer Trial may be installed?

install error - Visual Studio 2010 Error Message

Finally cleared up issue with errors regarding .NET Framework 3.5 sp1 installation on XP Pro SP3.  While installing Organizer Trial,new error occurs during the Trial install, showing a Null Error in the application deployment:

"Microsoft.visualstudio.tools.applications.deployment.clickonceaddindeploymentmanager.installaddin0"

Any suggestion on a fix or workaround.  Would very much like to install this Trial ASAP.