Apparently Vista was a "filler" OS until Windows 7 was ready. Remember ME & 200 before XP?
fast eddie: The major retailers (Dell-HP etc.) are the ones demanding MS to continue offering XP. They can't build "budget" PC's with the hardware that Vista demands to operate.
Roundtree: Vista is no better at deterring hacking than any other OS. No OS is going to stop/deter PC hacking. 3rd party softwares are the best protection.