Whew, it's ABOUT TIME. The next version of Office is going to be included in both 32-bit and 64-bit versions, and we can assume both will be on the same dual-layer DVD since both should be able to fit. Will performance be affected? Probably in massive workloads, but not so much for regular use. Doesn't matter though... it's nice to get anything in 64-bit, especially popular applications like this.
http://blogs.zdnet.com/Bott/?p=742
http://blogs.zdnet.com/Bott/?p=742