Getting new video card--leave the other one in, or yank it?

I'm about to take the plunge and get a new ATI Radeon 9500 Pro--would like to get the 9700 but right now the 9500 is a full $100 cheaper ($200 vs. $300), and from what I'm told it should be fairly easy to overclock it to 9700 specs anyway.So, I'm currently running a PCI GF4MX420--laughable, I know, but my old computer, which I had until last October, did not have an AGP slot, and the above was the best PCI card available. Ever since I got the new computer, though, it's been the Achilles heel of an otherwise great system (Sony P4 2.4G, 2 80G HDs, Windows XP Home, 512MB RAM, etc.). I assumed I'd just yank it when I got the 9500, but lately I've been reading posts here that talk about having dual video cards installed. Would this actually work? Would it give some performance increase? I'm a little wary, particularly since it would mean having NVidia and ATI drivers installed concurrently, which kind of sounds like a recipe for disaster based on what little I know about video cards.Don't know if it makes a difference, but I am also getting a new monitor and am thinking I'll at least try to run a dual-monitor setup, with my old monitor used strictly for gauges and navigational stuff. Is there a way to have the two monitors each run off one video card, and would this help performance?I'm grateful for any suggestions or help you can offer; I'm just looking to coax the best possible performance out of this system. (Really, the major benefit of the 9500 as I see it will be the ability to use AA and AF without slideshow-like performance; anything on top of that is gravy.) Thanks in advance!Marc