@Pyree Perhaps I should convert it to an mp3, and then just change the file extension! (Note, I decided to try this just to see, and it didn't work!).
Interestingly enough, I decided to see if it would work in XP Virtual Machine, so I booted it up, and sure enough, it works there just fine as a system sound!!! Won't work for Win7 but will work for XP running in a virtual environment inside of Win7!!!