I don't have anything that would qualify as vintage but my oldest machine still in operation is a custom built Core2Quad machine with 8GB of ram. It was more or less my main server. File, Web, development, DNS, email, later on VMs.
Would have been around 2008 when I built it, based on the OS file dates. (I may have reinstalled at one point, I don't recall). I was still living with my parents then so it sat in the basement with their computer as that's where the internet comes in and where the router is. When I moved to my house it was still mostly the main server for quite a while, it even got converted to rack mount. Then I slowly started to split stuff off. File storage went to a dedicated 24 bay server, so all the drives got moved, VMs eventually went to a dedicated ESXi box, started to move stuff like DNS and development to VMs. Right now that server is only doing email. I want to move from user based mailboxes to virtual users, but I can't seem to be able to do the type of procmail rules I want with virtual users, so I started to write a program that works like procmail then I just got sidetracked with other projects. I do plan to retire it at some point though as I want to play with different open source VM solutions and that machine as VT-D. None of my other unused machines have it. It's still a pretty decent machine too so I'd probably keep it as a test machine, or even repurpose it for something that I want physical hardware for, like a secondary VM server.
The sad part is, that server has more ram than our new work PCs and it is practically 10 years old. We got new PCs at work and they have 4GB of ram. WTF! 8GB should be the bare minimum these days.