Short bio: Computer Scientist, FOSS supporter (read more)
Tux Machines (TM)-specific
Most Linux users run a 32-bit distro, and many of them run a 32-bit distro on a 64-bit computer. The question is, why? We put 32-bit Ubuntu 9.04 head-to-head with its 64-bit counterpart to see what difference it really makes, and whether old compatibility worries are justified.
Thanks to extensive testing and feedback from the community, 64-bit Linux is as stable as 32-bit Linux, so there's little reason not to use it unless you have a need for a specific, 32-bit only app. Even Wine happily supports 32-bit Windows apps such as Microsoft Office or Half-Life 2 running on a 64-bit Linux installation, and cross-platform mainstays such as VMware, VirtualBox and Java have already been ported.
Of course, the other side of the coin is "if it's just as good for most users, why should 64-bit be used at all?" And the answer to that is "performance".