My anti-virus expired, i tried install update,its not accepted, cant access internet banking or secure sites..

I had norton anti-virus software installed late in 2004 and this expired end of last year. i was on holiday and forgot all about it, 2 months went past and then was told it was expired when i logged on. i am with bt broadband and they have anti-virus software but it wont do it all, so ii bought a new 2006 version (symantec anti norton virus) some months ago and tried to install it but it wont accept. i get a pop-up saying "virus protection out of date" etc. . . but it wont go away, i cant install new one and the old one wont go away! cant delete the old one either. what is going on? help, i cant get to any secure pages or website such as internet banking or if i really want to buy anything on the internet, the page is unavailable. .
Answer
You probably need to uninstall the old version first. go into start, control panel, find current programme listed, and delete. you should then be able to install new version.