Heavy emphasis on simple. I've never made an installer and I'd rather not have to learn much. A system that I could hand a pile of files to and it would make some smart guesses about where to put them would be ideal.
Go ahead and answer the general question.
However In my cases I'm stuck with some extra constraints. The program to be installed is written in VB6 (or is it 5?) and a few previous versions of VB, so it's not going to be updated any time soon. I have a running install and will have a Clean VM to play with So I'll be doing a loop of: run the install, find where it's broken, fix it, add that to the installer, revert the VM, try again. If anyone has a better approach I'm open to suggestions.
I MUST get it working on XP and I'd really like to also have something that will work on newer versions of Windows as well.