Links:
[1] http://linux.philosweb.com/drupal/category/it/software/software/os/linux
[2] http://linux.philosweb.com/drupal/category/it/software/software/os/microsoft
[3] http://linux.philosweb.com/drupal/category/it/software
[4] http://blogs.zdnet.com/BTL/?p=5433&tag=nl.e622
[5] http://www.zimbra.com/
[6] http://www.thinkfree.com//
[7] http://www.readwriteweb.com/archives/web_office_suite_comparison.php