Internet Problem

Hello,
My computer is a Dual Core Apple Mac , and i was on the windows vista side of my computer and i was on the internet as normal and i wanted to download a anti virus for my computer - obviousley i dident download the scareware antivirus2009 , because that is just world famous , but i got a internet security and i installed it , but it said i had to uninstall all the others for this to work , and i uninstalled all of the free editions of Avg , avira and avast! but when this new one was installed , it dident work at all and i clicked on the icon About 5 times and it dident work , however - The internet was on and it was still on showing the earth and flashing 2 monitors and it said local and internet but when i clicked on google chrome and internet explorer , both of them said it was unavailable !!

I am realy confused and would like a reply.

Thankyou . :)