Goodness gracious. Dual fast SCSI drives, 1/2 GB of RAM - nuts!
One of my clients has a full OpenACS install (though most features aren't turned on, but that doesn't affect the request processor checks on each page) along with some custom db-backed stuff I wrote. They didn't want to spring for the full server option, so I just charge them a few bucks to hang off www.zill.net.
The system runs Apache/PHP for a few small sites as well.
When I fired off a web-crawler on the site to pull down all the pages, the CPU was idle 90% of the time, and things stayed zippy.
When one of the Apache sites on the same server got zapped on SlashDot (dev.designharbor.org), CPU load stayed low then, and the OpenACS site kept cranking. Slowness was due to bandwidth, not CPU.
What are the specs on this monster system? AMD K6-2 350Mhz w/256MB RAM and IDE drives.
You can get a sub-$300 from TigerDirect.com or a zillion other places that will handle anything you can send over the DSL line.
I have run OpenACS/mod_aolserver on a Sparc 10 with 50MHz CPU - it was a little slower, especially on the parts of the site that were a little clunky or brute-force to begin with; but it was good enough for development use, actually. The Sparc was manufactured in 1993. If I had cooked it by tuning it (eg memoization) some more, it would have been fast enough to put into production.
OpenACS 4 may well require more, but then again may not, if some of the 3.x cruftage has been removed. It's still too early to tell.
