Visio is a powerful and complex drawing programm that can create mind maps.
Click on "Start" "All programs" and then "Core Applications". Visio os the one above Word.
When Visio loads you should see this...
If you have not got the short cut you can find the brainstorming diagram in "Business". Click on "Create" to begin the drawing.
Drag the main topic to the centre of the page and select the "Brainstorming" tab.
You can now use the brainstorming tools to help to complete your mind map.