The lines between "straight UNIX", Linux, and the BSDs are getting pretty blurred these days. Generally, proponents of the BSDs and proprietary UNIX systems tout stability compared to Windows and, yes, Linux.
Back in the day there was only one UNIX. Then AT&T got a bit restrictive with their licensing, and you had the BSD and System V split. That's it. That's how all this BSD vs Linux/UNIX stuff got started. The differences are mostly subtle...names for the kernels, a number of system calls, locations of init scripts, etc. They are really the same thing, at the core.
So on x86 you really have about three choices before you:
* Solaris x86 ("real" UNIX, mix of BSD and sysv, mostly sysv)
* Linux, take your practical/evangelical pick of distro
* BSD
With Solaris you'll find the hardware support is utter crap compared to Linux and BSD. But it'll run and run and run. Linux has far, far better hardware support. And it'll run and run and run. BSD has support in between. And it'll run and run and run.
Don't buy into the "X is more stable than Y" argument. True, you often find Solaris and BSD machines with ridiculous uptimes. But do you think those boxes are fully patched? I happen to make rounds to a lot of datacenters with Solaris installations, these guys are still running 6 and 7 in some cases, and haven't had security updates in who knows how long. And those crazy uptimes will go away whenever you patch a Sun box, since the recommendation is to *reboot* into single-user mode to apply most patches. Not just init 1 and back up, but all the way down and back up again.
Just my two cents. I find Linux to be
plenty stable.
