"One great thing about Linux is that you can transplant a hard
disk from a machine that runs a 32-bit AMD XP processor into a new
64-bit Intel Core 2 machine, and the Linux installation will
continue to work. However, if you do this, you'll be running a
32-bit kernel, a C library, and a complete system install on a
processor that could happily run 64-bit code. You'll waste even
more resources if your new machine has 4GB or more of system
memory, and you'll be forced to either not use some of it or run a
32-bit Physical Address Extension (PAE) kernel. Cross-grading to
the 64-bit variant of your Linux distribution can help you use your
resources more wisely.
"This happened to me with a Fedora Linux installation, and I
finally decided to migrate..."