Ummm... I have some new news since my last post. I have rid myself of the warbling effect. No, it is not any kind of stuttering effect that I'm referring to when I say "warbling". Imagine a flute playing a sustained high-C note. When at the end of his/her breath, you can hear the breath of the artist fluctuate in the tone s/he holds, which slightly shifts the note repeatedly, slightly above and below the perfect C. That's what I'm talking about.
Anyway, here's the fix: I peeked at the soundblaster.com web site thinking I should check for driver updates. I found that my drivers are already updated, but noticed a silly advertisement for the Lava! software, which I don't normally use. Well, I tried it. Guess what? When loading the soundblaster MP3 player with Lava!, it reconfigured the "Mixer". Result?
Flawless mp3 playback using the soundblaster player. So, I thought, hmm... this software works perfect. I wonder if the Mixer reconfiguration happened to also fix WinAmp's playback? Guess what.
Now, WinAmp is playing on my P-III JUST *FINE*! When browsing to this very site to post this message, WinAmp stuttered only a couple times. Now, I'm listening to it with flawless playback.
Thanks much everyone! Hope this note helps anyone else having this problem.