I believe I have the answer to my font problem. The offending typeface is the beloved Helvetica. Although Helvetica (a print typeface, mind you) looks good on Macs, it's all fucked up on Windows. Trevor Davis makes the comparison and provides a demo page of Helvetica sizes. You might not have this problem if you're using Windows and don't have the font installed. If you do and you have, it should look really freaky.
The typeface Arial complicates matters. Arial is derivative of Helvetica, and is the recipient of such scorn that some call for deferring to Helvetica before Arial in designing web pages. This approach is a problem. Although Arial has moral baggage, it looks good on a Windows screen. Helvetica looks like a mistake.