Please Help - Rogue Security Software

Please Help,

 

I have Norton Internet Security 2007 but it has expired and hasnot been updated.

 

i accidentally downloaded "System Guard 2009" :smileysurprised: and don't know how to remove it (i have even heard that i might have to erase the whole computer and then reinstall everything again)

 

I've heard that there may be a tool to remove it .  do you have one?

 

 

Sincerely Buttons11