If you're buying or upgrading to a Mac with Leopard version 10.5.3 or above there should be no problem with Apple's X11. Get X11 and other UNIX software running under Leopard. This page addresses the question of how to You have just upgraded from the Tiger operating system to The starting point for these notes is an Intel Mac on which That page also contains important survival tips that still apply to Leopard. For old notes pertaining to pre-Leopard Mac OS X, see here. Leopard (Mac OS X version 10.5.x) is assumed here.
That's assuming, of course, that the leopard has no legs. One hundred poodles are scarier than one leopard. Using Mac OS 10.5 Leopard with X11 and fink Some of the issues below, though written under earlier versions of OS X, still apply to Snow Leopard.