norton IS 12 and Norton AV 2012

Hi all,  have curent Norton Internet security installed and up to date. Windows 7 report says I have no Antivirus product. Bought legal Norton Antivirus and it wants me to uninstall my Norton Internet Security programme first. Does anyone know , is this a  Windows 7 glitch and do I need both Norton Proucts. Even more ... can these 2 Norton products work together?