Setting up a Linux storage server

[Phasma Felis]

I want to set up a headless server to hold/share backup drives for the other machines on my LAN (a Windows desktop and a Mac laptop), partly as a learning experience and partly because an old desktop is cheaper than a new NAS device.

I have a fair bit of *nix command line experience, mostly on OS X, but only a little with setting up and configuring Linux specifically. I've got a KVM switch to do the initial configuration. I've assumed that Ubuntu is the go-to distro for newbies, but I'm willing to be convinced otherwise. If possible, I'd like to have a VNC-accessible GUI on the backup machine, just for kicks.

Any major pitfalls I should be aware of before I begin?

[circumlocuted]

I'd suggest Gentoo, that's what I use for my headless server.
You'll learn a lot setting it up.

VNC is very easy to set up, most distros have a package that will install everything correctly in a headless configuration.
When you run VNC server, it doesn't control any existing desktop, instead, it starts a new instance of X11 and lets you control an internal virtual desktop that is only accessible via VNC.
So, you can easily have your favorite desktop and gui toys, while still being headless.

[Meteorswarm]

I'd suggest Gentoo, that's what I use for my headless server.
You'll learn a lot setting it up.

It's a trap!

While you would learn a lot setting Gentoo up, it would also take weeks to actually get it working. You'd probably be happier using a distro that is more newbie friendly.

I just used Ubuntu for my file backup server; it's what I'm familiar with, and does the job adequately. It won't eat your laundry.

[SWGlassPit]

I agree that Gentoo is not a good beginner distro, unless your side purpose is to learn the inner workings of Linux. A distro like Ubuntu will be relatively pain free.

[think_of_a_shape]

I've done this;
It ran a webserver for testing etc etc, an internal fileserver, and an external facing bitorrent. it also gave me a testing platform for Linux.
I used Ubuntu server (http://www.ubuntu.com/download/server/download)
The downsides are you have a box running 24/7 and cheap computers / computer parts don't like to do that. I had to have a monitor, keyboard and mouse for set up but once I had set it up I used SSH to get on there and thence install Webmin wich allows control via a web interface most things.

I like the idea of a VNC setup though, now, I just use a NAS box that promised to do webserver but doesn't really it does do bittorrent though, so....

There is also, if its just a "NAS from old PC hardware" scenario, you want...
http://www.freenas.org/