The Apple Cinema Displays are notorious for being incompatible with PC
video cards.  Maybe it's the cards, maybe it's the displays.  Many
cards will work when they get into Windows, but there are many reports
of BIOS/start-up screens not showing.  If you just spent a lot of
money on one of these displays, you probably don't want to keep a
second monitor around for when things go wrong.

Since the 30" Cinema Display is a very special case, let's take just
the 20" and 23" versions.  (See the other Google Answers thread about
the 30").

What PC cards work with the 20" and 23" displays where "work" includes
showing of BIOS/POST screens?

See this Apple note --
http://docs.info.apple.com/article.html?artnum=301066

I'm looking at getting an eVGA NVIDIA 6800.  Any predictions?

For what it's worth, my ATI ALL-IN-WONDER 9800 Radeon Pro doesn't show
the BIOS/POST screens (which I need to see), but ATI claims it must be
something to do with my motherboard BIOS settings not their card. 
(Motherboard is an ASUS P4C800E Deluxe.)