Already dual booting XP with Vista Home Premuim 32bit. I'll wait for more then Vista drivers when going 64bit since just about everything out is still 32bit at this time. For just the 32bit version of Vista expect to be replacing some desktop apps as well as finding some games won't install on it. For 64bit version of either Windows? Eventually 32bit will fade away but nowhere near as fast as seen with 16bit.