[sfhub]

You don't really close programs, you just back out of them or go to the home page. It's best you just let the system manage the apps for itself. I know it is difficult for those coming from WinMo where they are constantly worrying about the X button and whether it closes apps.

If you insist, get a task manager and kill off only high level apps like browser or maps. Killing off low level apps often results in instability. New users often just go in and kill everything in sight to see a high free memory count.