Inno Setup is simple, light-weight and covers a lot of ground. I've used it for 5-6 apps over the last 5 years and it never let me down. Highly recommended!
Before that I used InstallShield, which is one of these systems that are so complicated that they "offer" you to "utilize" their "professional services" to create your installations. In other words it's kind of a hack that only managed to build a customer base in the childhood of Windows because there was no competition. It's a bit like a 747 that runs like a Trabant.
The worst, by far, installer product I've worked with is "WISE for Windows Installer". This had me literally smash my mouse in the office floor in frustration. It is (or at least was, 4 years ago) utter crap and should be avoided at all costs. This is exactly the kind of software that those pesky license agreements are there for, else the publisher would be sued into oblivion...
