I have an OpenBSD firewall at home that keeps the gremlins out. It has been running on old 486 100Mhz machine that I have had since 1995. This machine originally had linux on it, and ran diald to connect me to the internet. Those were the good 'ol days. It worked pretty good, until I had lightning hit near the house, and it fried the USR modem and the serial port (which is on the motherboard). I put it in the closet (I hardly ever throw hardware away), and switched my firewall to a Pentium 90Mhz.
In 2001, I got broadband from Sprint with a line-of-sight wireless technology they tried in Salt Lake City. 256K up, 6Mbit down. Now the firewall didn't need serial ports, so I pulled out the old 486 and loaded up OpenBSD. It only has 32MB of memory, but it has worked great as a firewall and email gateway. It's not on a UPS, and the only time it has ever gone down is when the power goes away, about once a year.
The power went out two weeks ago, and the machine refused to come back up. I have a spare machine waiting in the wings for just such an occasion, so I moved the hard drive over to the new box, and was back in business.
I spent a while trying to get the old box working, but the motherboard is finally toast, it won't even POST. That machine has been great. It ran 24x7 for more than 10 years, while overclocked to 150MHz. Power supply is still the original one from 1995, same with the memory. I did put a new disk in it in 2001, but the rest of the bits are original. They sure don't build stuff like they used to.
This machine goes into the hardware museum; my collection of antiquated hardware going back to 1990 or so. Someday, I'll take pictures of all that stuff and post it online.