Setup with three monitors - best graphics card solution?

I have 2x 20" LCDs @ 1600x1200 and 1x 19" CRT @ 1600x1200. My current graphics card is a 6800gt (AGP), and it has one DVI port and one VGA port.

I'm thinking about buying a PCI graphics card with a DVI port for one of the LCD monitors. The question is, which PCI card should I go with?

I posted on another board, and according to one poster you might encounter problems when using two cards of the same brand, for example two nVidia cards in one machine. Does anybody know anything about such issues?

I was thinking about buying a new primary graphics card with two DVI ports, but my computer is getting kind of old (2yrs+), so in a year or so I might buy a whole new machine. So I thought I'd just buy a PCI card for the second LCD screen. I'll mainly use it for desktop applications, so I don't think it'll matter if it's hooked up with a PCI card.

I am not an expert at multi monitor set ups - but usually my rule is to stick with the same cards so you do not have driver issues.

if the 6800 and newer cards use different nvidia drivers - if the 6800 will not work with the new drivers i can see you might have some issues - if that is the case just sell the 6800 and buy a $50 card for the crt that uses the same drivers.
So if I'm using two nVidia cards that use the same drivers I should be OK? Is there some place where I can check if two cards use the same drivers?

Wow, sweet card. Too bad it only has 2 DVI ports, because I'll probably buy a third LCD in the future, and then I'd like it to have 3 DVI ports. If I'm gonna spend that kind of money I'd like to be able to use it in the future as well.