I have the opportunity to obtain 4 old computers. I have no need for a cluster other than as a project. What would setting up a linux cluster entail? How would I go about doing one?

Well, there's a "just add water" approach. A while back, someone released a cluster-ized version of Knoppix. I still have a copy of it. From what I understand, all you would need to do is network all the machines (physical connection that is), burn a copy of ClusterKnoppix for each box, boot up each machine one at a time, use the first machine to set up the cluster ID (the ClusterKnoppix CD has a utility to do this), and then have each other machine join the existing cluster. I never played with it much other than scan over basic information, but from what I read, it was that simple. Granted, you're running your cluster off a CD-based OS, which will probably be bad for performance, but you can always install that version of Knoppix to the drive if it works (and you like it).

Actually, a quick search on Google gave the homepage. It's still kickin' and is based on Knoppix v3.6: ClusterKnoppix

If you visit that site, you'll quickly see that the cluster uses OpenMosix. If you need detailed information about how to do this or that, then it couldn't hurt to get it straight from the source. They may even have documentation on how to do it yourself, but I haven't looked into it. Still, that kind of documentation has to be somewhere.

Also, O'Reilly printed a book a while back "Building Linux Clusters". I've heard a lot of people weren't very happy with it. I've never read it, but it might be worth checking out if you're hard up for more information.

thanks, but I'd rather not go that route, I'd prefer to set it up myself. Any other thoughts?

Ok, is there something wrong with the OpenMosix link I gave you?

That's the software used to create a cluster. They have plenty of documentation as well as an OpenMosix howto at TLDP. You'll need a modified kernel, and I'm sure some sort of network boot capability in each machine. Just because Knoppix uses OpenMosix does not mean you have to use Knoppix to use OpenMosix.

If you want a Beowulf cluster, then you'll need to do a search. I'd suggest Beowulf.org as a starting point.