Rebel Decade Chess

Unlike some incarnations of chess on the PC, the oddly named "Rebel Decade Chess" program is a hardcore chess simulation. It has a usable interface, but some people who are not hardcore chess players will be a bit overwhelmed by all of the options. I'm only a casual player (that is to say, I suck) so I can't really judge how good the computer is ... it whupped me pretty soundly though. :) The developer released several other versions of this game on their website if you're interested in more modern versions.