$420 budget, purchasing (one) of these come Monday.

[Degausser]

Alright, so my current system specs are as follows:

ZALMAN CNPS10X Performa 120mm Long life CPU Cooler
CORSAIR Enthusiast Series CMPSU-650TX
SAMSUNG Spinpoint F3 HD103SJ 1TB
G.SKILL Ripjaws Series 4GB (2 x 2GB) 240-Pin DDR3 SDRAM DDR3 1600 (PC3 12800)
MSI P67A-C43 (B3) LGA 1155 Intel P67
Intel Core i5-2500K Sandy Bridge 3.3GHz
XFX Radeon HD 4890

I game on 1680 x 1050. I haven't touched overclocking my CPU yet, but it's something I definitely want to try soon.

Here's my dilemma, and I don't know what to go with.

Choice 1 -
G.SKILL Ripjaws Series 4GB (2 x 2GB) 240-Pin DDR3 SDRAM DDR3 1600 (PC3 12800) Desktop Memory Model F3-12800CL9D-4GBRL
with MSI N570GTX Twin Frozr III PE/OC GeForce GTX 570 (Fermi) 1280MB 320-bit GDDR5 PCI Express 2.0 x16 HDCP Ready SLI Support Video Card OR GIGABYTE GV-R697OC-2GD Radeon HD 6970 2GB 256-bit GDDR5 PCI Express 2.1 x16 HDCP Ready CrossFireX Support Video Card with Eyefinity
Haven't decided which card yet. I was leaning towards the GTX 570, but considering my power supply, would that be possible?

Anyway, choice 2 -
2x CORSAIR Vengeance 8GB (2 x 4GB) 240-Pin DDR3 SDRAM DDR3 1600 (PC3 12800) Low Profile Desktop Memory Model CML8GX3M2A1600C9
with SAPPHIRE 100312-3SR Radeon HD 6950 Dirt3 Edition 2GB 256-bit GDDR5 PCI Express 2.1 x16 HDCP Ready CrossFireX Support Video Card with Eyefinity

Thoughts? Suggestions?

[Milkshake86]

Decently even cards i believe the 6950 might be a bit cheaper and probably the choice if your into BF3, 570 is not bad either i think id go w/ the 8gigs and radeon myself tho, 650w psu would seem adequate for a single card config.

[DeltrusDisc]

Your power supply will power any and all of the GPUs you listed just fine, however XFire or SLI for the 6970/570 it would need to be bigger.

Based on the GPUs listed, your best bet would be either the GB 6970 or MSI 570, personally I would go for the 570, but that's just me. Being that I also game on a 1680x1050, I know that you won't need the 2GB VRAM of the 6970, most likely. Hell, I've yet to use all 1GB that my 560 Ti has! The 570 has 1.25GB VRAM obviously, so you should be fine with that.

Plussss the 570 has a better cooler.

[taekvideo]

I'd recommend just getting 1 of those 2x4gb kits. You want more than 4gb in a high end system, but you'll need ddr4 ram before you need more than 8gb.
You should be able to squeeze this 6970 in with one 8gb kit. 900mhz isn't much of an overclock in the one you linked... you'd be better off doing the oc yourself, could get 950+ easy with the cooling on those cards (I got 950 no problem on my reference design cooler lmao).

[Degausser]

One of the main reasons as to why I'm hesitant to going with the 570 is due to the numerous problems I've read up about nVidia having drivers issues with Firefox and BF3. :|