MY PC WAS INFECTED WITH A VIRUS

Hello,
AFTER MY PC WAS INFECTED WITH ANTIVIRUS PLUS, I TRIED RUNNING AVG TO CLEAN IT & THE VIRUS KEPT KICKING IT OUT. I WAS ABLE TO RUN AVG ALL THE WAY BUT WHEN IT FINISHED IT ASK ME TO RESTART WINDOWS. AFTER I RESTARTED IT WON'T LOG IN IT STARTS LOADING MY SETTINGS & JUST BEFORE IT FINISHES IT STARTS LOGING ME OFF AGAIN I TRIED EVERYTHING, BUT I CANNOT LOG IN I NEED TO KNOW IS THERE A WAY TO PULL MY HARD DISK OUT AND REFORMAT IT? I DON'T CARE FOR ANY FILES OR PROGRAMS I JUST NEED TO REFORMAT MY HARD DISK WITH OUT LOGING IN. CAN ANYONE HELP ME? ANY IDEAS WILL BE APPRECIATED. THANX