I have now printed the eps files on a postscript printer and they do come out nice and sharp. Thanks for your help. My problem stemmed from not realizing that screen resolution was so much worse than (potential) print resolution and from not using a postscript printer.

Yes, I suppose it could be the renderer. I did not print the latest version of the eps file, just an earlier version. Your remark that you noticed the aliasing only on higher zoom levels suggests possibly that your screen's resolution is higher than mine and that the problem may indeed be in the rendering. Thanks for the tip about file links: I did not realize that this could be done in my earlier post. Here are the links to the files mentioned: plotFig1.mw and plotFig1.eps.