1) 4gb of ram is enough. If all your doing is gaming you can use that money on something else.
2) Switch the seagate hdd for a spinpoint f3 1tb.
3) 1 card solution is always better than 2 card solution unless your going super high end. Less problems, no scaling issues etc. If you can afford 2 460's you should be able to get a 6950 or 570 instead.
i5-2500K - Great choice 8GB of RAM for gaming - Like bavman has said, 4GB/6GB would be adequate. Asus P8P67-Pro - Yes, many hardware sites review this as the best SB board on the market. Intel 80GB SSD - Which one? Seagate Barracuda 1TB - No, no, no. Unless it's a 7200.12, do not get this drive. Go for the HD103SJ by Samsung instead. I think it's like $10 less and the best drive for the price-tag on the market, highly rated and very reliable. 1680x1050 - At that resolution, a single GTX460 will serve you perfectly and in the future you could buy a second as game-technology advances. Corsair TX750 - Are you planning to overclock? 750w is enough to power SLI-GTX460 config. but if you plan to overclock heavily with that i5-2500K then I think you should step up.
I thank you both for your insights, and I will be taking your advice, reducing the ram, getting the better hd etc.
One last question. If I skip the SSD in the short term and go with a single 570gtx. Do you guys think I still need a 750 PSU? The online calculators I've been seeing have been recommending a 550, though that seems a little low. Would a Corsair 650 cover me?
yes a corsair 650w would be enough for a 570, not sure about a second one though if you were planning on one in the future. I think the 570 would be a great choice and even if you decide to get a better res monitor in the future you'll still have enough power to keep game specs on the high end
Looks good. I'd go with a beefier single video card (570 or 580) at first. You can always look at adding another later (the prices will most likely fall as well considering the competition we've been seeing). Two of something beefier later beats two of something not-so-beefy later. 570s scale very well in SLI and a single 570 runs under the cost of two 460s (if you can... the 580 rocks!).
Knowing this I would beef up my PSU to an 850 or 950 with around 60A+ on the 12V rail. The beefier cards can require around 22A each under load. Also, measured with an appliance load tester, my wattage commonly reaches the 750s during gaming sessions with 2 580s, so if you go to a 570 or a 580 and are looking to add another somewhere down the line, plan for it.
A 650W PSU will cope with two GTX 460s in SLI, and two 560s for that matter. A quality 750W PSU will handle 2 x 570s. Though I always like to get more juice than I need for my PC to allow plenty of OC room and PSU degradation over the years
I am going to build a new i5-2500k system as OP.
The Asus P8P67 PRo is good but what is the difference between the other P8P67 models?(It is expensive compared to others. Question comes: Is it worth it? And why?). The graphic card will be a GeForce 560 Ti.
The important phase in this system for me is the CPU Cooler, the Power Supply and the Case. I want a cool, overclocked and no problem from power system.