This will be my first build, I have upgraded lots of parts over the years but I wanted to get out from under the prebuilt PC's this time around.
The only games I really play are WoW, League of Legends, Civilization and Diablo 3 (when it comes out). Other than that this will only be used for internet and encoding the occasional movie (as well as MS Office type stuff). I would like to build a system that will last a number of years. My current PC is a q8200 with a gts250 512mb card. This PC works fine but with my teenage kids there is too much competition so I need another PC.
Wow, excellent choices for the most part! The only thing I'd do is use a Sapphire card instead of a Power Color, but that's just my preference (also their Flex technology makes it really easy to setup multiple displays if need be) .
If you can squeeze it in your budget, you should try to get a 64GB SSD like the Crucial M4 to really round out the system - just store everything on your secondary.
And even if you don't plan to OC, the 2500K is currently one of the best CPUs that Intel makes - it should only be a few bucks more than the 2400. I'd also add a cooler like the Hyper 212 since the stock coolers that Intel includes are generally crap to begin with (I think they do that on purpose ).