I don’t want the yahoo toolbar and all the stuff on it. It’s slowing down my computer. Did I make a mistake putting messenger on my computer?

I have AVG anti-virus along with the yahoo toolbar running on my firefox. Sometimes I see stuff I typed in the yahoo search box in my yahoo toolbar. I don’t like that something is keeping stuff I typed out why is this? Is it a bug, a virus, spyware? Can other people or companies be viewing the information I’ve typed? Is my privacy being breached?