I don't use that much older hardware these days. But I do still use it!
My main system is however a reasonably new machine. It's an AMD FX4100 quad core with 16GB Ram. Video is via a PCI-E card on a late 2000s Radeon HD 4850. Mind you the full tower case it is in dates from the late 90s.....
Older hardware can be useful however, especially for single tasks. If you poke around on ebay for long enough you'll turn up some machines called "thin clients". These can be had for not much money and can be repurposed -
this website tells you how to do so.
Usually it isn't much more than a) find a power supply (most - but not all - use a "normal" powe supply), b) pull the DOM ("Disk on module") off, c) replace DOM with something like an IDE to CF or SD card converter with a short ribbon cable and then finally installing an OS. These devices don't use much electricty, are often quite small and could be used (for example) as a small, low-end server, an internet radio maybe even a standalone device to run an emulator - fancy a "new old" Commodore 64? And these devices don't usually cost too much although there are always the rip-off-o-thon places and people on ebay to look out for.
I went through a patch a while back trying out different ARM based devices but nowadays I find I'm moving away from the whole ARM platform. Reason why? The ARM platform is a mess, weird bootloaders that are never explained, ARM (as in the company) being linux unfriendly, propietary drivers needed everywhere, potential digital locks the list goes on. x86 stuff might not be *hugely* better but there's a lot more chance of getting it working.
Worst case you end up with something like the Efika MX Smartbook - still a usable device or it would be but because of propietary software it is effectively locked to an old 2.6 kernel - want a newer kernel you can run one, but then X is unaccelerated and then painfully slow. And then there's all the other devices to get to work - assuming you can....
Though it is no surprise. I find this sort of thing a lot with many manufacturers (especially phones) these days. Device appars, there's support for a year or two and updates then the manfuacturer ends up getting bored with it and support ends and the device gets forgotten about. Seems to happen mostly with phones - come buy your new phone then a year later dump it because the next one's just appeared....
At least a lot of the older stuff and that is x86 based will often work. Need to try it again but I have somewhere a very old (bought off ebay for not a lot!) Neoware Thintune thin client - an old thin client; 200Mhz CPU, 64MB Ram (I Upped mine to 256MB); Sis 550 video; 2 USB 1.1 drivers. Last thing I tried was puppy linux on it and it run quite well all things considered. Even an older debian worked!
As a sidenote and I apologise for going off topic, I'm also thinking here about flat screen displays and TVs. In a way some of this applies to (well to me!) finding a new flat screen monitor or display of some sort. I had to find an older model of flat screen TV (just recently to replace an older duff monitor and which would not take HDMI or even DVI) to use as a monitor as most these days are of the annoying "smart" variety - devices which spy and watch on you or might even refuse to work with full functionality, or constantly want you to "connect it to the 'net". Or it's >£500 for a smaller screen flat screen monitor. I wonder what I'm going to be doing when this screen bites the dust and *everything* is "smart" .... x.x
ljones
(Four computers, if I count my el cheapo laptop along; or 5 if I include my now ancient PowerPC-based iMac G5 along; or 6 if I count along that old HP "dc5100" SFF computer that I have, or 7 if - never mind 
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