In my 6294 class from Portland, ME, we had a individual concerned about Windows 8 and their investment in the 32 bit architecture. I still advise organizations to purchase the 64 bit platforms. The 32 bit architecture is next on the technology chopping block.
At the Consumer Electronics Show (CES) in Las Vegas, Microsoft demonstrated their work on Windows 8. They also announced support for Intel, AMD, and ARM chips. This included the x86 architecture. That means 32 bit will be around for another edition of windows. Below are two articles from Microsoft that talks about the platforms that Windows 8 will run on.