Well...two things come to mind. I suggest you don't look at Newegg's prices and just the actual parts you need and then shop around for the actual components themselves as Newegg generally doesn't have cheap prices.
I'd recommend you switch HDD to the Samsung 1TB Spinpoint F3 at eWiz.com for $59.99 using the coupon code LION0305. It's a much better performing HDD and gives more space for just $12 more than what you have listed above.
Next, if you live near a Fry's Electronics store, they currently have a combo deal of the Athlon II X3 440 with a 780g motherboard for $50 that's amazing.
That RAM is fine.
The GPU, I would suggest a 1GB 5770 especially if you're going to be using Anti Aliasing in games. If you wait until eWiz.com puts out another $15 off coupon code, grabbing a 5770 from there would be cheaper. The other option is to wait for Newegg Open Box 5770's but I believe the ones from eWiz are generally only $10-20 max more expensive than their Open Box products. I'll give more information when I get back home.
Edit: Back home now!!
As far as SATA cables go, your motherboard should come with straight/straight and straight/right angle cables so you won't need to buy any others.
Keyboard and mouse is completely up to the user. I personally like Logitech Keyboards. If you want something to game with, you're going to have to invest in a better mouse. Razer make decent mice but it's up to personal opinion. Just make sure you have at least 1600DPI. Now that I've been using 1600 and higher for so long, going back to using anything lower is brutal.
Cases and PSU's I don't like to give advice on but I generally wait for mWave to put up another OCZ 700w deal with an optical drive.