Avoided XP?
People that don't purchase new computers typically don't run out to buy the latest Upgraded OS. End users typically get it when they buy a new PC. XP wasn't quite as heavy as Vista and you didn't see people buying new machines and loading Win 98 on them like they are doing with machines with Vista.
Vista has exended the life of XP and this has never happened before.
Wanna rethink your statement about comparing the switch over from Win ME or 98 to XP Vs XP to Vista?