Dont bother going skt939. It is already out-dated by AM2, and AM2+ is even coming out in a few months. Look for an X1950PRO that has got only 256MB of RAM, 512MB is just unneeded.
Also, i dont think that AMD do an X2 that is 32 bit only do they?
yeah, they are called K7. as far as i know, they are the only ones that do..(but i dont know everything, lol)...that may even be REMOTELY availible. but they are seriously outdated. so...good luck finding one. they are outperformed by an intel celeron D, if that gives you any indication of their performance. you are going to have a hard time finding an upgrade here, my friend.
the athlon 64 (s939, am2) cpus are certainly designed to run 32 bit software as well as 64, i dont know what you are using that "just wont work"....but i would suggest updating your server software, as there is no upgrade for your system that will run solely 32 bit, without having some sort of transition path to 64 bit.
and not only the good am2...but all the am2 are 64 bit, man. so is every amd made in the last couple years.
this thread and "upgrade" questions and whatnot are to totally pointless if you cant run a 64 bit cpu...you have no upgrade. and any of those opty chips are loco expensive.
that s939 opty 180cd that you listed uses the same x86 instruction as an athlon 64. i dont know why that would work and an athlon 64wouldn't. but i would like to, if you would explain...?