For me, I think it's got to be a combination of oddest and oldest, although I've never had the chance to work with anything out of the ordinary, really. My dad used to be a computer programmer and set up some hardware on the side; I grew up around plenty of computers. Unfortunately he hasn't done a whole lot since the late 90s and he refuses to admit he's fallen behind the curve. As an example, we were cleaning out a bunch of old software out of a spare room and he refused to let me throw out a copy of Photoshop 4.0, claiming that it was still perfectly valid and even if it wasn't, Adobe would just give him a free upgrade anyways.
A few years back I dug up a pair of old Compaq laptops - both were identical machines, stock Windows 95, HDD less than 5GB, maybe 32MB of RAM... and somehow, he'd managed to get Windows 2000 running on one of them. The one that was still running Windows 95 worked as well as it did fifteen years ago, and for what it was it was fairly snappy. You wouldn't even be able to open any sort of document or program for the first twenty minutes or so with the other one.
Then there was the time he tried to set up a computer for my brother... This was back in early 2009, I think. My brother wanted a computer of his own, since at the time I was the only one in the house with a working laptop, and we couldn't go three months without someone fucking up the family computer somehow. After replacing it in 2005 with a top-of-the-line XP Media Center machine, our last family computer had been wheeled off to the aforementioned spare room; it was a Windows 98 machine, and probably the last machine I can recall my dad ever putting together from scratch. Of course, he decided that the hardware "isn't that outdated" and "for homework and Facebook or music it'll be fine". So after trying to set it back up, finding the hard drives were shot, and eventually digging up an unopened HDD apparently intended for that machine, he realized he couldn't actually get anything to install from the CD drive. So after driving around town for a couple hours trying to find some blank floppies (insisting on going to the big electronics stores and Walmart first, despite my insistence they wouldn't and didn't have them) we finally found a box of unused floppies for creating installation media. At this point, though, my dad decides that since it meets the minimum requirements of 64MB of RAM, he might as well install Windows XP instead. Somehow, we managed to get it up and running (I had to find a modded version of XP that was lighter on resources before I agreed to let him go with anything newer than 2000), and it actually more or less ran properly (as well as it could, given that it had half the minimum memory requirements for modern web browsers) for a few months. Needless to say, the first thing my brother did after getting a job that summer was buy himself his own working, modern laptop.
