If you try to run the installer without local admin rights you may see the error message "You do NOT have permission to install and deploy sharepoint solutions" in the SharePoint solution installer. Please
- login with apropiate user rights and/or
- in Windows Server 2008 don't forget to run the installation task "as administrator" with right click on the task
With SQL Server 2008 and 'mixed auth' was used on the installation, the BUILTIN\Administrators and DOMAIN\account (mine) were not set as SYSADMINs. By setting that using the 'sa' account, right clicking Security => Logins => BUILTIN\Administrators => Server Roles => checking sysadmin, the problem should be solved.