Dual Monitors with One or Two Video Cards

I have a Dimension 8200, Windows XP & a Nvida GeForce 2 MX 64MB AGP card. There is a VGA & S-Video Connector.  I want to have two Dell M991 VGA monitors with each monitor showing a different financial web site.  Dell Sales & Dell Support both said to just add a PCI Video Card.  I am considering a GeForce FX 5200 128 MB PCI card.  Then Dell Support emailed me and said that replacing the current AGP card might be a better setup, however, either would work.  They suggested either the GeForce FX 5200 128 MB AGP card or the ATI Radeon 9600 Pro 128MB AGP Dual Monitor Card.  I would have to also purchase a DVI to VGA connector.   
I know that the AGP bus is faster than the PCI bus, but my reason for upgrading is to be able to view a different web site on each monitor.  The only advantage I see to two video cards is that I could add a third monitor later.

Has anyone had any experience with two video cards?  Any problems with two sets of drivers?  Any suggestions?  Thanks!