4 DVI ATI on Nvidia board or play it safe?

I bought a new 24" LCD and want to run it alongside my 2 19" LCDs. Currently I'm running a BFG Nvidia 8800 GTS 640MB EE OC on an Intel Q6600 (G0) in a Gigabyte GA-K8N-SLI motherboard (nForce 4) with 8GB G.Skill 1066Mhz Ram. I had a couple spare Nvidia 7600s laying around but for the life of me cannot get them to run alongside the 8800GTS without blue screening right after startup (It's an nvidia driver issue).

I'm currently debating on how to handle the situation. I like to game and I'll be using the 24" at it's max resolution (1920x1200) so I need something that can handle it, but I don't want to break the bank. I don't want to change my motherboard as this one is fairly new itself. SLI would be nice but will probably double my costs so it's not a priority at all.

I was browsing Newegg and came across the Sapphire HD 4850 X2 2GB DDR3 sporting 4 DVI ports for about $330. ([url=http://www.newegg.com/Product/Product.aspx?Item=N82E16814102809][/url]) For my purposes this would be absolutely the most convenient option but I have concerns such as how well the card stacks up against my current 8800 GTS and whether I will be hurting myself by running an ATI card on an Nvidia board. If you read the user comments you'll notice some people having trouble with the ATI drivers but none with those provided by Sapphire, this also concerns me a little, but not much.

I suppose the next best option would be to get another 8800 GTS to match my current one. I'm not a hardware guru so I don't know whether mixing a 640MB card with a 512MB card will cause any problems as I don't plan on running in SLI as I said. This would appear to be the most cost effective solution however I feel that I would be shooting myself in the foot when it comes to the future.

And the third option of course is to buy 2 completely new cards. I don't keep up with hardware so I'm not to savvy on what's the best bang for your buck right now but I did see the stickied topic in this forum. Maybe others have better recommendations?

So let me know how right/wrong I am and what you would do in my situation. Thanks for taking the time.

Thanks for the quick response. I guess my only question left to deter me is if I'd be hurting myself by using an ATI card on an Nvidia board.

EDIT: Been googling around a bit and the general consensus of the tubes is that there isn't any problem running one on the other.