Since you have that much money you're in luck, you'll be able to get something that runs games 2-3 years from now (unless something big happens and they actually utilize all we can get at the moment).
Processor: You can get an i7 2600k, so that's what I would do. They're about $300 or so. If you want cheaper end, i5 2500k works as well and it's $220. AMD is cheap too but Intel is beating them at the moment, you can wait for Bulldozer if you want but idk when that's releasing..just that it's supposed to be this fall.
1. http://www.newegg.com/Product/Product.aspx?Item=N82E16819115070
Mobo: You can get anything that runs the newer Intel processors, some are better than others of course and I'll let someone else tell you what is better..I'm sure someone will have a link to a specfic one after a few posts. It mostly depends on what you want, say 2 or 3 GFX cards or just one (I think most come with 2 PCI 16x now anyways) and then SATA 3 or 6 gb.
http://www.newegg.com/Product/ProductList.aspx?Submit=ENE&N=100007627%20600093976&IsNodeId=1&name=LGA%201155 - Like I said, any of these will work..some better than others.
RAM: 4GB works, I do 8GB just to future proof, since it's cheap to get 8GB. If you want, you can go Corsair Dominator or another brand of that quality and go for higher speeds since you have the money, regular speeds you can get 8GB from GSkill for about $50 or $60.
1. http://www.newegg.com/Product/ProductList.aspx?Submit=ENE&N=100007627%20600093976&IsNodeId=1&name=LGA%201155 - Yeah it's more than 8GB, way overkill but good price for that many.
2. http://www.newegg.com/Product/ProductList.aspx?Submit=ENE&N=100007611%2050001459%20600006069&IsNodeId=1&name=8GB%20%282%20x%204GB%29
3. http://www.newegg.com/Product/Product.aspx?Item=N82E16820231314 - That's what I got and it works well.
GPU: I'm not to up to date on ATI, but I know the Nvidia 570 will do all that you want it to. It's about $300. The 560ti is cheaper and it'll run anything coming out I'm sure. But with your budget I'd go for the 570.
1. http://www.newegg.com/Product/ProductList.aspx?Submit=ENE&N=100007709%20600094002%20600095515&IsNodeId=1&name=GeForce%20GTX%20570%20%28Fermi%29- I like EVGA.
2. http://www.newegg.com/Product/ProductList.aspx?Submit=ENE&N=100007709%20600094002%20600107147&IsNodeId=1&name=GeForce%20GTX%20560%20Ti%20%28Fermi%29
PSU: 650w will work, I like Corsair so I go with them. It's about $100. If you plan on doing multiple GPU's you need to upgrade that.
HD: Any 1 or 2 TB will work, you might even be able to add in a Solid State to run the games if you want. By any I mean some people like Samsung, some like Western Digital etc, I'm sure you'll hear varying opinions on what is best. I like Samsung.
CD/DVD Drive: Asus has a cheap OEM one, that's what most people get. If you want a blu ray player it'll cost more, even more with a burner, depends on how much you have left afterwards I suppose.
Case: So many to choose from, I was going to get an Azza Hurricane ( I think that was the name), but I really want a full tower case..for the ease of use in putting the PC together. I would recommend that but they are kind of expensive. I don't know the benefits of a mid-tower other than the cheaper price. I am sure there are some out there though that are relatively easy to build in.
http://www.newegg.com/Product/Product.aspx?Item=N82E16811517010 - That's the case I was talking about.