So processor support is the last of our worries, and we should worry about the chipsets and all that other stuff?
It’s important to note that due to the need for “backward compatibility” (mostly with Windows) - processors must remain capable of running 32-bit x86 code for many years to come. New features of the processor must continue to function on “legacy” OSes with no additional support - and are usually enabled via drivers, or new OS functionality.
Processor companies have tried to “separate” their new processors from the previous generations with lackluster results (Pentium Pro comes to mind - and x64 hasn’t had a stellar takeoff yet)
Most CPU patches out there (like the BeOS Athlon patch for example) simply disable features of the processor that are incompatible with the OS.