Add me to the list of others who bought NIS 2005 and discovered it wreaked havoc with their system.I was also a "loyal" user back from NIS 2002 and opted for the "upgrade" against my better instincts. As far as being a firewall and antivirus solution, NIS 2005 is good, far as I could tell. However, in my case, it interferes with Windows XP operation, particularly the Windows Installer and Windows Update feature.Somehow or other, my Windows Update feature did not notify me of new security updates once NIS 2005 was installed.Moreover, I discovered, once updates were available for install, that I could not install them. Nor could I install something else (DirectX).After uninstalling NIS 2005 (and breathing a sigh of relief that it did actually install), I was able to install the software that was previously not installable.I went and downloaded Trend Micro's solution, but I'd suggest anything besides NIS 2005.