Solution: Don't record with an Athlon!! ;-)
Just kidding. Sorta.
A couple of things...
First, the whole "arctic silver" craze is nothing but a money trap. Don't get sucked in. Unless you absolutely need your cpu to be 1 or maybe 2 degrees cooler, don't waste your money. Go to your local electronics store and ask for thermal compound for heatsinks, and for $5.00 they'll give you a tub that will probably last the rest of your life.
Take a look at this:
http://www.hardocp.com/reviews/cooling/compound/
For what it's worth, I use a Zalman CNPS-3000 Plus CPU cooler. I got it here:
http://www.sharkacomputers.com/
Sharka and QuietPC are both Zalman retailers - I just found that Sharka had lower prices for what I wanted.
Now, this cooler can't be used with an Athlon. I record on a PIII due to the heat/noise issues caused by Athlons/P4s. The CNPS-3100 Plus is supposed to be okay for Athlons up to 1.4 GHz (with the fan running in silent mode), though.
(Quick note, for those of you running PIIIs or Celerons with Intel retail HSFs - the Intel retail units for these CPUs are very quiet, and I wouldn't worry about switching in those cases.)
Also, I run an Enermax Whisper 350W power supply. This PSU is BY FAR quieter than any other unit I have ever used. I highly recommend it if you're using a noisy power supply.
I've been talking with a friend recently about starting a website about products for quieting your computer. There are an awful lot of misconceptions about heat and noise that nobody seems to be willing to take the time to clear up. I'll let you all know if it ever comes to pass.