I've just installed my first 64bit OS in the form of Ubuntu's Intrepid 8.10. However, I ran into some problems trying to get my SSL VPN up and running (but that's another story). I ended up needing newer versions of libssl and libcrypto. However, OpenSSL's configure scripts didn't want to believe me when I asked it nicely to make 32bit version. After struggling with various arch, target and -m32 settings, but having 64bit headers still included in the resulting Makefile; I eventually found this blog entry, which pointed me to the helpful 'linux32' app, which is part of the util-linux package. It creates a shell which wraps calls to uname to make it look as though you're on a 32bit architecture. Problem solved.