There are a lot of other cards that work as well but are not on the list. Sometimes they have straneg issues or need to be tweaked a bit, but they work. check http://www.realtimesoft.com/multimon
for more information on different configurations that people have used. Their database is invaulable. Also, realtimesoft has a program called ultramon
that is really useful for operating multiple displays, especially for enabling and disabling various cards and such.
FWIW I'm running a GF2 and an old ATI Rage Pro Turbo card (Xpert98). The usefulness of the extra desktop space you get from dual displays is incredible. It's probably the best upgrade I have done in the last year as far as usability of my system is concerned.