What largely broke me of it was being a Windows 7 beta tester for over a year.
I watched them iron out all of the bugs to a perfectly balanced OS which doesn't need any tweaking. In fact, tweaking has become synonymous in my mind with corrupting a nearly perfect OS.
OK, I still get my tweak off by disabling Offline Files whenever installing Ultimate, or running the batch file to turn off WMP Sharing service on other installs - the only thing that will keep it turned off - or editing video effects on low resource machines.
But it's such small potatoes that the only way to replace the addiction is to do about a dozen clean installs a week, help fix another dozen or so online, spend more time surfing and at the gym.
Oh, and don't try to confront a tweaker because they can be vicious as a jonesing addict, which most are