Looks like an okay build, but I have some suggestions/questions.
Do you really need the 2x2GB RAM? I mean unless you're upgrading to 8GB, it really isn't worth it. Most games and applications don't use more than 2GB. Plus 2GB sticks cost a lot more than 1GB.
Now with that motherboard, you could just overclock your Q6600 like I did with mine. It's not worth it to buy a 3.0ghz quad core, my Q6600 is at 3.4ghz with simple cooling. I'm not sure if your CPU cooler would overclock as high, but this is what I have:
http://www.ncix.com/products/index.php?sku=25509&vpn=BTF90&manufacture=ZerothermAs for the case, the CM690(which I also have!) almost always has some sort of discount on some website. Right after I bought mine for $50 they had huge discounts, some starting at $30 USD. So if you can, keep on the look out for them.
Everything else seems fine. I'm a budget guy so I don't buy sound cards and all of that, I just use onboard which works great if you have a good motherboard like yours.
