Thanks for the info/advice. I knew these C3 chips were low performers, but I didn't know they were quite that bad. They're mostly designed to be used as headless servers, DVD/MP3 home theatres etc so the majority of people wouldn't mind that. I was hoping to also do a spot of emu gaming so maybe I should rethink.
What I've done to silence my current setup is change the noisy fan in the PSU for a 12db Papst one by cutting out the old one, clipping off the 4 pin power plug of the Papst fan and soldering it into place. This is practically inaudible.
I tried using the same kind of fan to cool the CPU but the CFM rating wasn't high enough to keep the temps down - I was getting temps in the region of 80+ so I swapped this for a higher CFM Papst fan rated at 20db. 20db should be very quiet in theory, but it still grates on my nerves. Either my ears are very sensitive or Papst are underestimating the noise levels. Probably a bit of both actually.
Then there's the fan on my Radeon 9000. I don't really know the specs of this since it's the factory default one. It's quite small as are most GPU fans, probably a 50mm so that explains the whine coming from that. Over at www.zalman.com
you can get a passive GPU cooler which should work to shut that up, but then I'm still left with a stupidly hot Athlon, always the way with AMD chips sadly.
I'll do a search for these Antec PSUs in a sec and see what I can find out. Whatever I do I definitely want to get rid of this Athlon which will mean changing mobos. Like you say, I think a Celeron is a good idea since they're easier to cool so I'll be able to run a slower fan.
do a barebone system called the Terminator which includes a PSU with no fan. The only fan in the system is a large exhaust fan which is dynamically controlled by the BIOS depending on the temp of the system. They've been getting excellent reviews. The only downside for most people is the lack of an AGP slot. Anyway this is another option I'm considering.
If anyone is interested in these Shuttles, a new AMD model is being released mid-January. It will have built-in Geforce graphics equivalent to a GF4 MX. It's said to be even noisier than the previous models, though that's not an issue for everyone.