Well, I've finally done it. After all this "soon I'll" and "eventually" my PC is pretty much dead silent. The Corsair Power supply was the biggest impact, compared to the Thermaltake it cut the noise level by a good 5dB or so. I've also used an open 3-pin connector to hook up the 2-pin fan on my Asus graphics card to my fan controller, undervolting it to 7V. It still cools the card fine, and is silent. (That Asus TOP cooler really is quite impressive!)
The second 3870 in my system has currently been removed until my Arctic Accelero S1 rev 2 arrives. The stock cooler's irritating buzz was preventing the 'silent' tag be applied. I also used the opportunity to do some mild cable tidying. It'll be better after I put the second card back, but for now I think it's adequate.
So, this is what she looks like now. I'm posting this image, and the one that shows how I silenced my hard drives in the official PC building thread.
oooh nice. The Freezer 7 Pro on my CPU reduced the noise the stock fan usually makes by about 5db, it's really silent even though I'm not that bothered about it, but the DVD drive makes me think it's the end of the world when it's loading something/burning a DVD :S