foobar2000
Free software that will batch convert .wma files to .mp3 files AND convert all of the tags properly. I did have to play with the settings under
File->Preferences->Advanced->Tagging->MP3
Set "Force Preferred....etc."
Set "Preferred Tag Writing Scheme->ID3V2 + ID3V1
Set "ID3V2 Compatibility....etc."

Very nice. The GUI is definitely not written for n00bs but pretty much everything that you want to do to convert is available. You WILL have to play around with the settings. The Converter allows you can add a custom converter and put your favorite command line settings in the box for Lame or whatever. It will batch up a ton of files and convert them with whatever you want. Once again, very nice.

Small footprint (12MB memory) but is an enormous CPU hog (YAY!). It used LAME on both CPUs on my P4 Hyperthread (1 file on each) so it processes twice as fast as other converters!!! However, this does make it an overnight, set-and-forget converter is you want to convert 1,000 files or something.