What is meant in Newegg's descriptions of processors by "64-bit support"? I know that 32-bit processors can handle 64-bit (or even 128-bit variables). Does this refer to memory allocation? That is, is it able to reference memory addresses beyond 4 GB when a processor that has no 64-bit support can't? Or, does it refer to it being faster with 64-bit variables? Windows calculator uses a 128-bit floating point variable since Windows 98 at the earliest known (back when 16-bit processors were probably still in use).
64 bit support refers to multiple things, primarily that it uses a 64 bit address space or close enough so that it can run a 64 bit OS, secondly it refers to the architecture as 64 bit CPUs have slightly different architecture with more registers than 32 bit only CPUs have.
How large the int and FP units are is a different thing and not related to being 64 bit support.
not all cpu's support 64bit some are still about that are only 32bit. the reason that they advertise 64bit support is that it easily helps the end user identify the product as able to use a 64bit o.s. yes to programmers it means other things like bigger addressable area and so on, but for joe public it just helps cut through the sales crap.