Upgrading from a 8800GT/750i mobo yay or nay

So a couple months ago I built my rig so I could play the latest games @ 1680x1050 maxed out. Which most game do, some could use a tiny boost though.

IT was your standard fare

E8400
Asus P5N-D
8800GT
750w PSU


yada yada yada.

So far the system is great and does everything I need it to do. However my only gripe is the Motherboard has a video corruption error, which can't be helped because the entire nforce 700 series is affected. Now I know EVGA released a fix but Asus hasn't posted an official bios, but they do send you a updated bios through support to fix it, but its confirmed this fix doesn't work. I bought this board because of SLI, and was going to add a second 8800GT until I heard about the ATI 4850. Now I have been sitting on money from 2 pay periods AND this guy is buying my Laptop for $500. So I got the money to burn.

My question is this, should I add a second 8800GT OR should I get rid of both the 8800GT and Asus P5N-D and upgrade to a 4870/4850 crossfire?

I don't want to get a GTX280 as I feel it is way overpriced. I figure I can get $300 for my 8800GT and Mobo.

Is a upgrade worthwhile or just a waste of my time?

Any suggestions would be helpful. IF you do feel a upgrade is worthwhile how about some suggestions of your own? I mean I haven't owned a ATI card since the Sapphire 1950XT which was a few years ago. Plus you might have something diffeent to suggest. My mind isn't set I just want to make my PC even more kickass.

Woohoo!

Make that DS4. All dq6 does have 2 more sata ports. It has smaller heatsinks.