The oldest machine I have is a Gentoo installation from early 2002, however because of the very different philosophy of Gentoo regarding upgrades it is misleading to say it is 2001. Unlike amost every other "Distro" in the world, Gentoo has no "version numbers" My system that I installed and that is still running from Feb. 2002, is just as up-to-date as a system that you would install today with the latest release.
The ONLY reason that Gentoo needs to release a "new version", Say 2008.1 or 2008.2 is to include support for newer hardware that would prevent you from installing the 2002 version onto a machine that say has a hard driver controller or a network card that wasn't in existence in 2002 and isn't supported by the kernel that is included in the 2002 boot disk.
If the hardware on your system is supported well-enough to be able to boot the 2002 install disk and be able to see your hard drive and network card, it doesn't technically matter if you install from the 2002 or the 2008 CD. Once you do an "emerge --sync" and "emerge -uDNav world" your system will be the same system.
Unlike other distros you aren't tied to a specific kernel, say 2.6.7 for the "life" of the distro, or samba 3.2 for the "life" of the distro until the next "release" of the distro. Once a particular packaged is deemed "stable" by the Gentoo developers, it is marked as stable and once you sync and update the system it is now running that newer version of the program. It doesn't matter if the original version was samba 3.1 on the 2002 CD, and the latest stable release of samba is 3.4, once you sync and update, you will be at 3.4 If you choose, you can also specify in the /etc/portage/package.keywords to have a particular program, and only that program to be "cutting-edge" Meaning it hasn't necessarily been marked as a "stable branch" by the Gentoo Developers. Say samba 3.4 is the latest stable release, but 3.5 has been released, you can tell the system to allow the 3.5 version of samba, but not have the rest of the operating system in the "unstable branch". I have a dozen things on one of my servers that are in the "cutting edge" branches, and other servers where there is nothing cutting-edge. You can also choose to have the entire system use the most recent release versions, kind of like running Debian Sid. Also like Sid, expect there to be lots of breaks and bumps when it comes update time. Like everything in Linux, it's YOUR chose to do what YOU want to!
You can also choose to only update a particular package with "emerge -u packagename" (emerge -u samba as an example) you can also update samba and all the packages it depends on, and only those packages with "emerge -uD samba" There are many many other flags available for the emerge feature.
So, I have a Gentoo system that was originally installed in 2002, has moved across 3 hard drives, and 2 different CPU/motherboards as time has passed, but it's still the original install, and technically I've done nothing up "update" the system, because with Gentoo there is NO "upgrade" as you would think of any other distro having. Even though this system has never been "Upgraded" it's still as up-to-date as a Gentoo system you would install today with the latest install CD.
This is why I LOVE Gentoo Linux, especially for long-term systems/servers. Yes, you have to pay attention when updating the system, and because EVERY program is compiled from scratch, it takes longer, sometimes a LOT longer for the updates to complete, but you have a faster system, optimized for your particular CPU and hardware, that never has to go through an "UPGRADE" to be current.