I remember reading about WiX a while ago, back I when I was doing more packaging. Never really gave it a good look at the time though.
Recently I was looking at creating a few custom installers (like an updated OpenSSH for Windows) and I immediately turned to NSIS. I started reading through the doco, and then remembered something about an xml based Windows Installer tool... WiX. A Google later I had found the binaries and a veeeeery nice tutorial.
And let me just say, it fucking rocks. I haven't even scratched the surface of what it can do, but I'll get there and share my learnings along the way.