Quiet PC Spec Help?

Hi All,

I'm wanting to build a new computer soon (my first build, so I know very little about hardware), one of the main objectives is to get it quiet. I'm not expecting silence, I just want to make it as quiet as I can on my budget without compromising performance.

It'll be for programming (incl CUDA, so I need nVidia graphics), gaming and 3D work (not enough to justify a workstation card).

I was originally planning on building this last year but I didn't have enough money, so I've got a similar 'base spec' as I had then, the same components are even more expensive than last year though!

Case: Antec P182 - (I'm reluctant to pay £120 on a case, especially since it was £70 last year, but it's supposedly one of the quietest, so...)
Case Fans: 2x Noctua 120mm 1200rpm (but slow them to ~700rpm)
PSU: 650W TX Corsair PSU
CPU: Intel Core 2 Quad Q6700
CPU Cooler: Noctua NH-U12P CPU Heatpipe Heatsink with NF-P12 premium fan
Mobo: Asus P5Q PRO
RAM: 4GB (2x2GB) Corsair TwinX DDR2 XMS2, PC2-8500
GPU: 896MB XFX GTX260 XT, 2000MHz GDDR3, GPU 621MHz, 216 Cores (if the stock cooler on this going to be loud?)
HDD: 640 GB Western Digital WD6400AAKS Caviar Blue
DVD: Pioneer DVR-216DBK 20x DVD±R

Total comes to £760 delivered, my maximum budget is £800 - I already have an OS, and extra HDDs.

If anyone could make any changes, or scrap the spec and do a better one for me it would be much appreciated,

Thanks.