There is no mesurable lost in applications speed, whether games or business, which makes sense, since most common applications will be 32-bit for a long time.

Why did Microsoft make a separate 64-bit version Window SKU? It was to make a clean break with the old driver models and some obsolete API, old shell extensions, etc. The 64-bit version is more secure and fixes some holes. It was to do exactly what people are asking them to do: make a clean break with some of the oldest things. They also dropped all support for DOS and 16-bit windows application in Windows 64-bit.

It is precisly part of the plan that people will be gradually buying new machines with Vista 64-bit. That’s how you deal with a very large user base.

If windows 64-bit still ran all the 32-bit old drivers and old DOS apps, then you’d complain that Windows is held back by all the backward compatibility it needs to do. If they breaks it, then you complain it isn’t as backward compatible..

Leopard is not a true 64-bit operating system, the kernel is still 32-bit, that’s how they “remain compatible”.

I’d also point out that Apple makes no 64-bit applications, none at all, including their FCP suite. I’m only aware of Houdini for OS X being 64-bit. On Windows, all the majors CAD, multimedia, and video (Autodesk, Avid, Avid, Softimage, Maxxon Cinema 64, NewTek) are 64-bit. Pretty much all the drivers you need including graphics drivers are there in 64-bit form. 64-bit was really made for these markets, and server-side. It’s ok if the consumer doesn’t jump on 64-bit immediately.