I can tell you from personal experience, you won't be able to do more than 2 non DisplayPort Monitors. The only other way would be with an Active Adapter which is over $100.00 each.
Printable View
I'm got an active DP adaptor that only costs AU$49
Available from PC Case Gear here:
http://www.pccasegear.com/index.php?...ducts_id=14786
http://mugginz.com/hostage/2010/Jul/GC-ACTDP.jpg
Works with my Acer AL2416W 24" DVI LCD screen and a ATI 5870.
Haven't used it much because I'm waiting for 10.7 to enable Eyefinity but when using one DVI screen and another one via display port connected via this adaptor 10.6 auto detects the screen and makes it available for use.
It would seem the price of these things is finally starting to get realistic.