Do task killers actually work? Possible Duplicate:
  Do I really need to install a task manager?  




I am using ASUS Transformer. I think it uses Ice Cream sandwich, from the UI. I tried many task killers but wonder if they actually work. When I kill tasks, I still see them when I click the "Window selector" 3rd button of the bottom left screen (the 2 boxes). They do appear to take a while to load, so I suppose the tasks were killed but the thumbnails are still there?
Task Killers do generally "work" in that they kill tasks.

They don't "work" in that most apps that you'd want to kill due to running constantly will simply be restarted by the OS, and Android already has appropriate task management built in.  A task manager will mostly just drain your battery and waste your time.

See also: How can I stop applications and services from running? and the question eldarerathis links in the comments.