"without loosing sound quality." makes this a non-starter. MP3 is lossy compression. Something's gotta go.
Even with this being a non-starter, you can head to most computer stores and find WMA to MP3 convertors on the shelves. Try one.
I have a number of music CD's that I have collected over the years. I used Media Player 9 and placed the songs that I like on my computer in .WMA format. I recently purchased a music box that plays .MP3 CD's. I want to take the songs off my computer and put them on a cd in .MP3 format so that I can play them on this box. I am looking for a good program that converts .WMA to .MP3 in a group not indivually, without loosing sound quality. I don't want to sit down and convert each file indivually. Oh, one other thing, the program can't install any spyware.