Mark,
Keyspans are good. I have only one, really old, obscure piece of software which won't work with them.
I got a rig programmer from RT Systems, and picked up one of the RTS-03 as they guaranteed it would work. It did, and with everything else I tried it. Somewhat brand X, but it uses the FTDI chip set.
http://www.rtsystemsinc.com/othercables_template.cfm?cfid=3106444&cftoke... 931273
Something to consider is an adapter by Parallax. Go to WWW.PARALLAX.COM and put in the part number 28030. It uses the FTDI chip set, and is designed to be used as a programming controller rather than just a communications interface, so it brings out a few more lines than does the typical USB to serial converter. Some rigs may need those. With the USB A to mini USB B cable it is about $20. I have never found a rig or similar control function it will not support, even when making house calls. The only drawback it that it doesn't really have a case. With a little Exacto knife work you can modify a cheap plastic RS shell to fit.
Alan WA4SCA