Nice build. I only have one gripe with it. The GTS 260 is pretty much a rebranded 9800GTX+ and you won't see much more performance increase out of it. Why nVidia does this, I don't know. To save production cost and increase profit I guess.
So you can do two things with the GPU card.
1) Swap it with a 9800GTX+ for about $20 less with MIR
2) Swap it with a 4870 1GB for about $10 more
I would go with the latter.
You will also need an aftermarket heatsink fan for you CPU if you want to OC. Xigmatek makes a very affordable and effective HSF for about $30 dubbed the S1283.
Depending on where you live, microcenter has the I5 for $159.99 -- but it's only good for in store pickup, so if you're not near one, not so helpful. Picked up mine last week, and you'll love it! I built an almost identical system, but with a 4850.