Just got done doing a new build that now rocks, and you have pick most fo the same things....do the 2500K fo sure, the board I would switch to the MSi GD65, more bang for the buck, I also spent more on a SSD drive 256gb instead of a new card, and I am very glad I did. My GTX260 OC, now hits over 150 on all maps, and most hit 250 - 299 mark on easier maps. On the PSU i would recommend doing the corsair 750w, it has a much more stable single rail. New system put my windows rating to 7.6...changed my video card rating from a 4.3 to 7.6. by changing the cpu, board, and SSD.
Plus now i boot in like 10 - 15 seconds...It installed windows 7 in 11mins.