This is rapidly becoming my favorite Linux distro.
For BSD, I like FreeBSD 6-series, and with Windows, I'm either recommending Windows 2000 for older machines, or Windows Vista for the new ones, but you have to set Vista up correctly. It's tempermental.
The same thing is true of CentOS, but for different reasons.
CentOS is not the flashiest desktop, and it has the kind of slightly stodgy install that comes of designing for the least specialized use, knowing that people will be plugging your system in under radically different conditions. Ubuntu doesn't do that. Windows does, mostly with hardware support. BSD is pretty good about it too.
You could describe CentOS as a conservative Linux distro, because it doesn't go far beyond being able to consistently replicate known demands. It's not sexy, but it is reliable, and fairly fast even on old hardware.
I've got a couple archaic Dells with this on it heading out to people who would be perfect Asus Eee customers if they were in a buying mood. They're aiming for the 90% of common tasks that can be done with a browser, email client, and simple word processor. An 800 mhz Dell with CentOS, AbiWord and Firefox does what they need.
I'm taking a different approach in that I'm not presenting these systems as software platforms, like Windows machines are. I'm presenting them as portals to the rest of the net and common tasks. They're not primary machines, but handy appliances like blenders or TVs.
We'll see where it goes. Either way, CentOS has earned a place in my repertoire, alongside other distros (and commercial OSs).