There's a nice little article over at Informit.com about adopting Extreme Programming (XP) practices in an organisation. Having gone through the adoption process in the past, I'd put myself somewhere between a toe-dipper and a cannon-baller. One of those guys that eases in up to the "cringe-point" where the water temperature makes your stomach want to run up into your chest, and then just dives in the rest of the way. It means that the initial period is a bit slow, but less disruptive, while it doesn't drag out the finish once your team becomes comfortable with the process.