I have used iTunes for managing my music for my iPod and it works
great; however, I still prefer to use Windows Media Player for all my
other comms apps.

My problems is that I receive my voicemail messages as .wav files from
Vonage, which I prefer to listen to on Windows Media Player (WMP). 
However, everytime I use iTunes, iTunes overrides my WMP settings and
makes itself the default player for .wav files.  Each time, I have to
go back into WMP and manually reset WMP to be the default for .wav
files.

How can I prevent iTunes from overriding WMP?

Since iTunes is fighting for control, you have to go into iTunes.

Once in iTunes, click on the Edit menu, and then Preferences.

Make sure "Use iTunes as the default player for audio files" is
unchecked. Then it will won't steal the file associations each time
you use iTunes.

Thanks for your question.

skermit-ga

Thank God it was something easy -- thanks, skermit!  This has been
driving me crazy for months...