Originally Posted by Difflugia
Two popular ones are GO Launcher EX
(the one I use) and ADW Launcher
. Install one of them and the next time you go to your home screen, you'll get a choice of apps to use. Select the new app and make it default.
My preference is Nova Launcher
Whenever Google offers discounts, Nova is usually one of the participant devs; Google is bound to cross the 50B downloads any moment now, so a sale could be coming - keep your eyes open for a possible sale on the prime version of Nova.