are you going to overclock your i5 2500k cause if not it's not exactly worth it
To really take advantage of a processor as fast as a 2500K, or higher, I personally wouldn't use a video card lower than a 6870 or 560ti, but that's just me. You'd get a 3 fold increase in fps over a 9800 GTX in most games.
This will be a good build as soon as you get a GPU. Until then, it'll be wasted potential, but that's your choice. Everything looks good.
+1 By then you will probably find better deals on the things you are trying to buy.
True. I hadn't thought of that. That's probably a better idea.