Mark asks, "How can I convert a bunch of wma files to mp3? My daughter just got an iPod and most of the music on her hard drive was ripped from CD using Windows Media Player."
In general, converting one compressed audio format to another compressed audio format is a bad idea. Both WMA and MP3 are lossy formats, which means some of the original audio data (in theory, inaudible sound) is missing from the WMA file you plan to convert to MP3. You will lose additional audio information from the file during conversion. If you have the original CD, you'll get a better sounding MP3 file by re-ripping the tracks. When you're talking about hundreds or thousands of tracks, re-ripping might not be a practical option.
Since your primary concern is iPod compatibility the obvious option is using iTunes to handle the file conversion process. By default, iTunes is set to convert WMA files to AAC format during the import process. AAC files created by iTunes are fully compatible with all iPods, but might not be compatible if your daughter decides she wants to play the files on your car stereo or some other player. By switching a preference setting in iTunes, you can convert the files to MP3. Open the iTunes Preferences and click the Importing tab. Choose MP3 encoder from the dropdown menu and select a quality setting comparable to the quality of the WMA files.
If you aren't interested in converting your MP3 files for an iPod, there are other ways to get the job done. Of course, you can still use iTunes for the conversion process; but it may not be your preferred music manager. I'm doing all my batch WMA to MP3 conversion with freeware app WinFF.
If you'd rather purchase commercial software, I've been a fan of Digital Media Converter for a long time. Along with convert your audio files, Digital Media Converter is among the best solutions I've found to convert DVR-MS files to other formats, which doesn't apply to your WMA to MP3 problem, but may prove useful in the future.