Notes: The following table tells you what file to download for your architecture and platform:

NOTE: releases starting with version 1.9.9.5 fixed an issue with "lsb31" packages that prevented them from working on Fedora 14 or any distribution that ships with zlib version 1.2.4 or higher.

i386 = 32-bit Intel-based
x86_64 = 64-bit Intel-based (aka AMD64)
 
lsb30 or lsb31: use for all modern Linux-based distributions (i.e. Fedora 6 and newer, RHEL (or CentOS) version 4 update 2 or newer, and Ubuntu Hardy (8.04.2) and newer)
lsb13: use for 32-bit RHEL (or CentOS) 3
centos3: use for 64-bit RHEL (or CentOS) 3
darwin980: use for MacOS 10.5.8 (Leopard)
darwin1030: use for MacOS 10.6 (Snow Leopard)
darwin1110: use for MacOS 10.7 (Lion)
win32: use for Windows