I currently have a 24in 1080p monitor for gaming and a 22in 1080p secondary for music, sys monitoring, etc.. and I am using onboard graphics. Needless to say I can only use 1 monitor at a time and even then I can only play some games and in low quality at that. I want to play more gpu intensive games liike Crysis 2 or Metro 2033 in 1080p on max settings and still use the other monitor for hw monitoring so I'm wondering if a 570 would be enough or will i need 2 560s? If I go with 2 560s I'll have to get an sli motherboard also, and my limit is about $450, give or take, which would mean 1 560 and the mobo now, and another 560 later. OR I can just get a 570, keep my current semi crappy mobo and get an nh-d14. I have no idea what to choose and I don't want to end up wasting money on something I don't need.
I reccommend the two gtx 560ti's. It will attain almost 140% the performance of one gtx570 when overclocked and maybe 20-30% more at stock. Dont go for the gtx 570; if you have the money for two gtx 560ti's. Get the best gpu(s) you can get for your budget, it will help alot for games in the future such as battlefield 3 etc. It is a common and often a good decision to buy a nice gpu now, and then when you are unsatisfied with your framerates, get another for a nice boost.
On another note, seeing as you have a amd phenom II, why not wait until 2012 to get a nice cpu/gpu/mobo upgrade package? The bulldozer, ivy bridge, and the new nvidia gtx 6xx and amd hd 7xxx series are coming out soon. You'll probably be more satisfied with those shiny new pieces of hardware.
I'd say go with a GTX 570. For one you have an AMD board based on the 880 so SLI is out of the question for you. You can get an SLI motherboard and another 570 latter (probably along with a bulldozer or better CPU ^_^)
I actually think I'm gonna wait and go with the radeon 7xxx series. I usually go nvidia but I feel like I'm gonna get a 570 and get screwed over when the 7xxx series drops and I could've gotten a way better card for the same price. Thanks though!