The oldest piece of hardware I own that I still use is a keyboard I got with my original PC. It's about 11 years old. I also have a 1GB Hard drive installed as a secondary drive in my current pc from my second PC. It's about 8 years old, but still works!
I had actually thought I had stopped using all of my old computer hardware, yet after a slight glitch I had to fight with my computer accessing some of the network storage I am using I found that I am still running a SCSI card from the mid 80's. This was a proprietary card that runs a 12 bay SCSI CD-Rom tower. I have totally forgotten that I have had this setup on my network for additional usage. I have grown so used to having all of this available I never think to check on it. I do have to admit that the Dual Pentium 100 Pro processors do a heck of a job relaying cd storage over the network. Date stamp on the card was 1986.