HDD activity ruins any kind of Music from WMP11

OK, I have XP Pro working from my desktop - I put this machine together and
it's been working fine except for one issue which just cropped up recently.
It's an AMD 64 3400+ with an ASUS Mobo - about 2 years old with 1 gB of RAM
and a 160 gB SATA drive. I use the on-board AC97 sound device - I don't have
a discreet sound card in this thing. In WMP, if music is playing (from <any>
source - MP3, Optical drive, streaming) and the hard drive kicks on as it is
want to do occasionally this zaps the music. There's a extremely rapid
machine-gun style (almost a buzzing sound) noise that occurs with the same
frequency as the HDD light flickers. During really intense HDD activity the
music will almost grind to a stuttering halt until the HDD settles out, then
it's fine again. This is the main reason I've ruled out raw electromotive
interference because the "noise" symptom actually develops into a
halting-like interruption depending upon the varying intensity of the HDD
activity level. IOW, if I really poured on the load on the HDD, I'd probably
be able to stop the music altogether for a good couple of seconds at least.
I've carefully looked at the running processes while this interruption comes
on and can't see anything taking up huge CPU time. It may be too quick for
me to notice it too. The SATA drive is fully defragged. In experiementing
with this I've killed every process I can including firewall, AV, stuff
running in the background and from the systray. I've not messed with
Services at this point - I don't feel they're a part of this. But, they
could be, right?

What I'd like is some advice or help on how to set up the SATA drive so that
Windows will stop reading/writing to the drive so often. Or maybe there's a
pagefile setup that will work better. Pagefile right now is set: Initial
Size: 1536 Max Size: 3072. Processor scheduling and Memory Usage are both
set to "Programs".

Thank you kindly for any suggestions!