How to ready pc for NIS 2009 fresh install

I have OnLine Armor as a firewall; BitDefender AV and Spyware Dr.  I’ve decided to remove all and use NIS in January when my subscriptions run out.  I don’t want to remove these security devices before the installation since I’ll be downloading NIS and I need the old protection till the download is done.  I’m supposing NIS downloads and saves to a designated file.  Then I can uninstall my old security software and install NIS.  Sound right?  If I’m missing anything, let me know.