Really need some advice here. Been going back and forth on this build for over a month now and just can't make up my mind. I have a budget of $2500 (which includes a 24" LCD monitor, KB, and speakers). One of my main indecisions is wether to go SLI or not. I want to be able to have max res or close to it @ 1900x1200 with my monitor. If I can save a few bucks great, if not well that is why there is a budget! hehe
I cannot see your list. You may want to adjust it.
It really does not matter though because I will provide my opinion. If I were you I would go with an X38 or an X48 motherboard and go with crossfire instead. From what I have heard crossfire scales better than SLI so you will be getting your moneys worth more with crossfire.
I would also wait for the new ATI graphics cards to come out. The value will be even better. Nvidia boards are just not stable enough in my opinion. With all the data corruption you hear about involving the 7xx series I would not bother. As an owner of a 680i chipset I can also testify that I have dealt with data corruption as well. Nvidia chips just aren't reliable.
That link provides a little info on how both SLI and Crossfire work. Granted it is a little dated, however you will get the idea. Pay special attention to the "performance" section. It shows that Crossfire outperforms SLI.
Since you are in a hurry I would either buy a really cheap card and simply store it when the new cards come out in June, or buy a really high end ATI card and crossfire it after the new ones come out and the prices on the previous generation drop. I am not sure which solution fits your situation best. That is up to you.
From what I have heard OEM versions do not take kindly to hardware updates. They tend to stop working because Microsoft does not expect people to update their hardware in their Dell's. I could be wrong with this and I am sure someone can correct me.
SLI works just fine and there is no data corruption with that 780I board, some 790i boards had a problem with it but that’s being fix just like it would be for ATI. The 9450 is a good cpu for the price at the microcenter.com.