Me neither. It's installed itself from somewhere you have visited. Smileycentral.com, as well as others, push this toolbar and it can be bundled with their free software. I've had this nasty a couple of times and removal instructions are here .. make sure you follow all the steps otherwise it won't be properly removed: http://www.pcselfhelp.net/spyware/mywebsearch
Those my web search tool bars are nasty. My mom had one on here computer and I had to take it off because she didn't know how. Smiley Central is definitely a huge perpetrator with this tool bar and I find that most a vulnerable if they are using Internet Explorer. You should try Firefox if you're not using it already. It's an effective browser with customization for No Squint(makes web print bigger) to Ad Block (which takes off all those annoy ads you find on websites). Just a thought
Carolina:Good job on the tips to remove the toolbar!