I'm with Rob - the state of the art is inadequate, and even if you built everything from source (which I tried a few years ago) you'll find so much of the free software out there is not 64-bit clean that it just won't work.
That's weird. I've found most open source packages are 64-bit clean, no problem. This is because there have been 64-bit UNIX machines for at least 15 years now.
What most people seem to be complaining about is trying to run a mixed 32/64 bit system. This is a bit trickier, but it is possible to do it right.
IMNSHO Redhat and SuSE do this right, but the debian based distros do a horrible job of it. RedHat and SuSE have seperate /usr/lib and /usr/lib64 directories in the way SGI pioneered years ago. For some reason the debian people went in some other direction, maybe they've fixed things though, I last looked into this a year or so ago.
In any case, we have a 31-machine cluster all running x86_64 SuSE 10.2 with no problems, and that includes running both 64 and 32 bit executables on it. I also worked on a Linux lab here that has been running x86_64 RHEL Linux on a bunch of AMD machines for 3 years now with no problems.
So I think it's a bit alarmist to tell people to stay at 32-bit, especially since if people don't use things and report bugs then there never will be any progress.
If you're running Linux in the first place, you should have at least a little bit of an adventuresome streak going ;) Although I am a bit biased, seeing as I currently am maintaining 8 different architectures worth of Linux machines (soon to be 9).
Vince
