With the box together, the next step was to pick and install a Linux distribution.
I'm not plugged into the Linux world, and the whole hooraw over which distribution is best bores me for the most part. Again, I'm used to one OS: you install it, it works, you go on about your business. Still, I do have opinions.
The very first one is that any distribution that calls itself GNU/Linux is automatically disqualified. If I wanted to run a GNU OS, I'd run Hurd. Oh, right, you can't, can you? For Richard Stallman to insist on horning in on the credit that rightfully belongs to Linus Torvalds is on par with the rest of his approach, and speaks poorly for him as anything but a fanatic. I'm not doing this as a political statement, and I will not support Stallmanite politics in any way I can possibly avoid.
There's also another battle I want to stay out of: Unity. Canonical seems to shift positions, and UIs, with each major release. I'm staying the hell off that treadmill. Unity seems to be universally reviled. This entire affair is different for me: one OS, one UI. You can customize the UI, though, something my roommate prefers greatly over OS X; me, I have no particular plans to do so.
That rules out the most popular Linux distribution, Ubuntu. Nevertheless, there are advantages to following the crowd, most notably in finding answers on the net. When your support comes from Googling things, the more people using the system, the better.
I also want a system with all the moving parts included, or at least easily integrated from standard sources. I don't care if my graphics drivers are open source. I just care that I can install them and they work. The same goes for multimedia codecs.
Fortunately, there's a distribution that's based on Ubuntu that doesn't kowtow to Stallman and has a wide user base, with all the moving parts included or easily added: Linux Mint. I haven't seen any real complaints about it anywhere. Being Ubuntu-based, Ubuntu and Debian packages will install on it cleanly. I also found a fair amount of hits when I randomly Googled around.
I actually made this decision a few weeks ago. I downloaded Linux Mint 13 with MATE, since that seems to be their preferred UI, and set it up on a virtual machine under Parallels. The install went cleanly and quickly. I wasn't able to run Firestorm under it, but that's because Parallels 7 doesn't virtualize the graphics adapter completely and the Catalyst drivers wouldn't install. It seemed reasonable enough to me, so I burned a DVD.
Fast-forward to yesterday. I had this shiny new machine all set up and ready to run, so I stuck the DVD in the drive and brought the system up. I was quite pleased to see Mint start right up with no problems, and recognize the hardware with no fiddling. I started an install to the hard disk, and it rightly complained at me when it discovered the machine wasn't connected to the net - and when I plugged the Ethernet cable in, it quit complaining, without my having to tell it to check again. I did partition the hard disk myself, to create an 8 GB swap partition just because running out of RAM is catastrophic without one. I gave the rest of the disk, 992 GB, to one gigantic root partition. From there, the install went along smoothly.
I did have a bit of trouble installing the Catalyst drivers, but it was PEBKAC: I tried installing the post-release updates first, and it didn't work. I then tried installing the originals, and that worked fine. The system called for a reboot after that, but I had a doctor's appointment, so I just shut it down instead.
When I got back to it, it came right up off the hard disk. The next step was to install Firestorm. I sucked it down off of the official download site and exploded the tarball. When I tried to run it, though, it complained at me about missing libraries. I should have remembered that from running it in the VM: the ia32 compatibility libraries needed to be installed. A quick trip through synaptic - and I do mean quick; it downloaded 243 packages and installed them in under five minutes - and that was done. Firestorm then came up with no further complaints.
I poked around a few places I use for framerate testing, and got a quite pleasant surprise: one scene at my home that gives me about 24 FPS if I'm lucky on the Mac Pro did better than 50. Even better, the scene that I notice most on my roommate's computer ran at 46 FPS with nobody else in view, and later that night, at 34 FPS with six avatars around.
For a Mac user, the installation was about as easy as installing OS X from scratch. An OS X user wouldn't have to install the 32-bit compatibility packages, though; they'd already be there. On the other hand, optional packages that need installing take slightly more work than synaptic requires; there are very, very few of them, however, so the user only has to do it maybe once for a standard system. The update process works as well as the OS X Software Updates, though again there are more of them; Apple bundles them in bigger bundles instead of updating 162 different packages.
So far, so good. It does what I set out to have it do.