I don't know all the specs off hand but one of my servers is a core2quad with 8GB of ram. Not sure how accurate of a way to tell this is, but a dir of / shows system folders from year 2008. So it's like 8 years old. Uptime is 823 days.
It used to be my main server, so it ran mail, web, DNS, development, file, VMs, the works. Eventually built a separate file server, so moved the drives over to it from that server, then got a separate VM server so moved the VMs over. Eventually made VMs to house DNS, development and other stuff. One VM is going to be for mail but ran into an issue that I just have not gotten around to solving. Once I get around to it, I can finally retire that old box. Idealy I will use it to experiment with different VM solutions. I originally put VMware on the VM server since it was quick and turn key, but I want to look at KVM/Qemu. They just require tons of reading/configuration which I did not feel like dealing with originally.
It's incredible how power efficient the new Xeon based stuff is though. I've actually clocked my newer servers at under 100w from the wall. Pretty impressive when my workstation is like 400w lol. Add on video cards will tend to do that.