Talk me about 64 bit systems...

Suppose you just buy a new piece of computer, with 64 bit technology and everything you consider cool. And suppose you'd like to install a GNU/Linux system on it.

As you've got a 64 bit architecture, I think you should use a 64 bit distribution, right? Once you installed it, since the 32 bit instruction set should be still available, you should be able to run 32 bit applications as well.

The only thing that may prevent you to run it would be the use of shared libraries, since a 32 bit application could never dinamically load a 64 bit shared library...

Is there a leak in my reasoning?

>>10
Except that with x86, it's not just about the pointer size. The x86-64 architecture doubles the inventory of GPRs, which means that you don't have to push as many values to the stack when making function calls, which means that everything is suddenly a lot less cache-sensitive. In other words, the x86 -> x86-64 move is a specific case where, by sheer coincidence, everything does indeed get faster.