For those needing a USB-to-serial adapter, Cyberguys has one that's reasonably priced. See
IOGEAR USB to Serial/PDA Converter Cable GUC232A - Cyberguys.com
The ad says it doesn't work with Vista or Windows 7 but it gives information on how to get the drivers for those systems.
I'm not endorsing the items. I don't need it and have never tried it. This is for information only.