As in the title: How can Alt+F4 be disabled in Windows 7?
AutoHotKeys is good but I workarounded it much more simply with a remapping of the windows key with a small utility called SharpKeys. It can simply map F4 to another key with a very intuitive interface.
You can use a simple AutoHotkey script:
# Remaps Alt+F4 to "no action" !F4::return