To 64-bit or not to 64-bit? My thoughts.
So there has been a discussion going on Planet Ubuntu about whether one should run a 64-bit distro on their hardware. As has been expressed, for most users, it doesn't make a difference, except come 2038.
However, if you plan to do any music/audio/video production on Linux, 64-bit is the way to go. The biggest advantage, is being able to make use of much more memory for your video/audio/graphics work. That alone is enough of a reason, however running 64 bit helps in other ways as well, such as being able to use binaries that have CPU optimizations such as sse enabled by default. For 32-bit binaries, while most modern CPUs support these optimizations, the binaries have to be built for the lowest common denominator, that being, machines that may only have sse, and not sse2, or may only have mmx. All x86_64 (64-bit amd/intel) CPUs have had things like sse since their inception, so if the program can take advantage of it, it will.
These optimizations can make a big difference when processing that huge image, or rendering that video clip, or mastering that 24 track audio recording, probably saving you enough time to get that other important thing done that you needed completed yesterday. :)