OpenArena rocks, that's for sure
Since it's based on ioquake3 it still has very basic default settings, which I'd suggest to change because
most people do have more than a P233 now
I mean it's set to 640x480, bilinear filtering, medium details, and so on. At least trilinear filtering should be the default, not everyone understand what this means but it really AFAIK is be the default for years in games.
Another thing, even with maximum details, is that the LOD for the round boxes (with health in them) only displays them "round" if the player is nearby. This should IMHO have no effect on new systems (or even a 5-year-old AthlonXP2400+) to at least have a details setting which gives "high quality".
Also automatic downloading is off by default, since this is an essential feature IMHO this should also be changed to give a better experience to newbies.