John King wrote:
What about CentOS, isn't it made for servers?
Well, just about any Linux distro can be made for servers, depending on what you install on it, really.
CentOS is loosely based on Red Hat / Fedora, and also comes with a package system.
I don't use it myself, though, but experience tells be that Ubuntu might be slightly better if you're just starting out on Linux. I believe the Ubuntu edition installed on a Linode is without X windows (ie. much like the "Server" edition you can download from the Ubuntu website).
If I were you, I'd start off with Ubuntu, and later move on to CentOS once you're more comfortable with the basics of Linux (in general). That's just my personal opinion, though. If you want similar package systems, you have Ubuntu and Debian in one group (both use APT), and CentOS and Fedora Core in another group (both use YUM).
What's great about Linux, is that with all the different flavors of it simply draws up the selection to personal preference.
Each distribution is just as stable as the next; how well it runs depends on your own fine tuning of it.
Considering you're absolutely new to Linux in general, I'd go for Ubuntu, as I believe it's more beginner-friendly.