Win7 will have more consumers onboard due to it's expansive compatability (still in development with windows updates). Vista had nothing but headaches for alot of people! Also, the hardware made today runs better on Win 7X64.. The main issue is software.. 64 bit applications are the future of the PC biz, however we are in a slow moving transition to 64 bit authoring. The difference between 32 bit apps and 64 bit apps is a little like comparing dvd & blue ray.. both have a nice picture, but unless you have an expensive (did I also mention BIG) HDTV & Home Theater you may not notice much difference. That was not the case between 8/16 bit apps when moving to 32 bit.. the improvements were quite noticeable and hardware requirements were made possible by the go-go days of hardware getting cheaper by the day, instead of by the year (what we've got today). There was also much easier consumer acceptance. With the economy not doing well too, that throws a couple of roadblocks in front of mass adoption of fully compatible systems.
The future of innovation on 64 bit is exciting because the tech industry now has a peek at what the future holds: SUPER (MULTI) TASKING! Applications that used to bring a single core processor to a crawl are lapped up by multi-core processors. Consumers will see the benefits of the innovations in the next 5 years.
Being able to open (about) 10 explorer windows, a productivity app, disc burning software, a media player app, instant messenger app, and a few other goodies, while gaming in another window (on another monitor) are just the tip of the iceberg that are 4+core processor systems!