Sounds like instead of extending your desktop you want to split it or have 2 separate desktops (one showing on the TV and the other on the laptop).
This article points to a number of freeware titles that will do just that. Try each one and see which works best for you: http://www.techsupportalert.com/content/How do I get a spit monitor on my laptop?
What you're looking for is called ';Extended Desktop';.
There's a guide for it here: http://maximumpcguides.com/windows-7/extend-the-desktop-to-multiple-displays/