Windows 7 - Thoughts on my new set-up

This might seem a bit long but, I wanted to hear some thoughts on both the losses and gains.
My current setup consists of:
MB Abit AN8 32x 939 board
CPU Athlon64 3700+ 2.22
3 gig DDR 400Mhz memory Dual Channel
SLI Nvidia 6800GS (2)
Power Supply Corsair HX520W
Various Sata hard drives and such, no worries with those.

As a gift I got a bundle from the egg this week which had the following:
P5Q Pro Turbo motherboard.
Intel E5400 Dual Core 2.7
2 gig of DDR2 800Mhz
750gig Hard Drive
Since there was no new video card with this and the board can run dual ati cards but not sli Nvidia and the motherboard doesn’t carry either an ati nor Nvidia style chipset ( P45/ICH10R ) can I get away with a single Nvidia card from my current setup until I manage a decent ATI card or if I am just wanting to run a single card would I be better with a faster Nvidia card?
I’m guessing the video card will be my bottleneck for the moment. I expect to see a nice jump from the single core AMD to the dual core Intel. Also, if I figure the memory side though I am losing a gig at the moment my speed basically doubled or will I still see a big hit there as well until I get more memory.

Any thoughts would be appreciated.

Yes. But, you do want to upgrade that video card when you can. I personally suggest sticking with Nvidia.
I have an ATI 4890 that I am pleased with it's performance, but drivers still suck.

You will still notice the speed difference in a big way. Where you will see an issue, is games loading.

So, It all depends on what you are doing with the system. 4G is obviously better than 2 if you are gaming. You won't need more than 4G, unless you are doing big video/audio editing and rendering, or virtual machines. Don't let someone talk you into more than 4G if all you are doing is gaming. You will be wasting your money. Save it for a big video card, and/or SSD.

Aah well that is good to know I can use one of the Nvidia cards till I can spring for a bigger/faster one.. I have always had good luck with the Nvidia cards so will probably go with a new one of those when I can....

Definitely will at least go with 4 gig for the memory as well and while I don't do alot of gaming I do run some Vmware machines occasionally and know more memory will help there. I should see a nice boost with the dual core and faster memory initially even with those.