Can't say anything about soundcard, but the A64 and Chaintech board should be great. However, if the 3200+ is a Clawhammer (1024KB L2 cache, 2GHz), you may as well get the 3000+ Newcastle (512KB L2 cache, 2GHz), as the performance difference is quite minimal. If it is a Newcastle 3200+ (512KB L2 cache, 2.2GHz), then awesome. The additional 200MHz gives more performance than the extra cache.
The motherboard you've selected should be fine. I'm rather partial to SiS for instanely reliable drivers, but currently there are no really nice mobos with their chipsets for AMD CPUs, so the NF3.
-Video: A Built by ATI 9600 (fanless) would be good, or a Sapphire Ultimate (Zalman heatpipe cooler, fanless), OR a low-end/midrange Leadtek if you want NVidia, also fanless (others are fine, too, but Leadtek uses bigger heatsinks on the fanless ones than most). If you are a gamer, a Sapphire 9600 Pro Ultimate would be the perfect card for quiet at a nice price. Passive, not too expensive, and good mid-range performance. You get what you pay for going for more, but if you aren't into high resolutions (1280x1024+) or anti-aliasing and anisotropic filtering, it should be enough.
-Case: Antec SLK3700-AMB or Sonata, for ease. The Evercase E4252 is great as well, but does require some work to quiet down. Not a terrible lot of work, but a little more than replacing case fans.
-PSU: If you go with the Evercase or another case, (check out SPCR forums for more on the cases), get a better PSU than they come with. A good quiet one would be the Fortron/Sparkle FSP-300-???. You can spend more and get truly silent ones, if you wish. Also, wattage means jack. A nice 300w like the Fortron, Enermax, Antec, etc. will be much more capable than the cheap 550w ones you can find around. Again, check Silent PC Review.
-Case fans: Panaflo L or Papst. If these are too loud, a fan controller to undervolt them.
-Internet: if you have an external cable or DSL modem, the onboard LAN from the motherboard will do. HOWEVER, you want to get a router. A router will have a basic firewall built in, which is practically a necessity for internet-connected machines now.
-HDD: Whenever it comes to a new drive, forget IBM. Seagates are pretty quiet, and now have 5-year warranties. Just FYI

.
-CPU HS/F. The retail heatsinks aren't bad for AMD anymore, but hardly quiet, either. A Zalman radial flower (any of them that work with the A64s) would be a great choice (but will not fit in a lot of cases), or a Thermalright or Alpha heatsink and Panaflo L, but generally you'll get better performance at lower fan voltages with the Zalman. The exception to this appears to be the Coolermaster Hyper6, but it is heavy and would give a lot of torque to the motherboard, and to top that off, would cost more ($50 USD + ~$7 USD for quiet fan vs. $35 USD for any but the newest Zalman radial flower) and be harder to install.