I'm no apple fan, but how is Mac OS X (I'm assuming Server Edition) not up to the task of being a hosting platform? It's basically a LAMP stack minus the L. We're not talking about Facebook or Google levels of traffic here either.
There's nothing wrong with it as such; there's just no reason to bother with it. It's certainly better than Windows. Linux is just easier to strip down to a lean server configuration, and happens to be free.
The hardware is compact, cheap, reasonably powerful, efficient, and they are willing to colo it for a pittance. I would consider buying one of these, maxing out the ram, installing linux on one of these, and hosting it with them. It would pay for itself in less than year in terms of savings compared to a low end dedicated server, and have more firepower to boot.
