I've answered my own question, for the most part. A friend suggested an HDMI-to-DVI adapter, which you can find on eBay for a couple of dollars. He had one that he didn't need and gave it to me, and it worked! Only thing was that it needed to be DVI monitors, not VGA monitors, because the HDMI port puts out only a digital signal. Fortunately I had matching 19" DVI monitors available, so everything is working.