I own Media Monkey myself, and while the Original Poster may have gotten the idea that it's just a conversion program, it's more:
A music Library able to do any and all that WMP does, better. Mainly because the library is organised MUCH better. You can sync portable units (iPod, Zen, Zune, cell phones), rip CDs, burn CDs, etc.
I would recommend that program to anyone. It's free, yet it's not. There are some features not included in the free version. If they aren't essential to you, you got, IMO, one of THE best musicplayer/-organisers/-conversionprograms out there.
If you are content using WMP as your player (I am not, I use it ONLY to watch DRM-WMVs. Everything else, MediaMonkey and VLC), I'd like to recommend BonkEnc: http://www.bonkenc.org/
For video, I recommend SUPER: www.erightsoft.com/SUPER.html, which can also do solely audio. A LOT of choices can be made in this program, but you can also just drag and drop, choose which format, and hit Encode.
The difference between BonkEnc and SUPER, is that since BonkEnc is a pure audio-encoder, it also has the ability to get info from online database, or insert your own tags to the file. SUPER just does conversion, but it covers a wider area of conversion. Should the need arise to do more than simple WAV to MP3, you have it. No external codecs needed for any of the two latter programs. Well, BonkEnc needs to download the VQF codec, but if you don't know why you should use it, and you're looking for WAV to MP3, you don't need it.