Alright man, despite what some of these guys say, I'd say you're on the right track but we need to make some modifications.
1. For the video I'd go for
this. You'll get good performance with zero noise (from the video card at least).
2. Motherboard, I'd go for an Asus board but the Abit should do fine.
3. CPU, the Q6600 is fine, just get a G0 stepping and you'll need to find the right heatsink/fan that will fit in your case. I'd also recommend having ONE intake fan pulling directly from the outside (ie. A hole in the case right over the CPU). This will ensure you have the coolest air going to your CPU first.
4. Just get one hard drive. No need for two. If you want, get a nice 7200rpm laptop SATA drive. It will reduce heat and open up your case for more air flow. If you need more hard drive space, do it on the back end (use a NAS). WAY easier to increase space too.
5. Memory, you're fine there.
6. DVD drive, you just need one. However, I'd try to pick up a LG Blu-Ray/HD-DVD combo drive. They're not that badly priced and you'll have an HTPC that will be able to play all formats.
7. And finally the case. I'd highly recommend
this one. Great looking case and allows for some great cooling (hole over the CPU).
Obviously you'll also need some nice low noise case fans to go with it. And if you set them up correctly, you should have a nice HTPC on your hands that you can also play games on.
The ONLY reservation I have with this setup is if the heatpipes on that video card will fit inside the case. But if they do, you're good to go.