First off, thanks for all of your responses. I am new to the forum, but it looks like a very useful resource.
I did that test, and it did not work either. I only have a handful of albums in aac formation that I bought from iTunes. I buy most mp3s from amazon, and they use mp3 V0 Extreme. I rip CDs to flac and convert to v0 Extreme as well, so 99% of my collection is in mp3 format. For what it is worth, I cannot tell the difference in sound quality between the iTunes Plus AAC and mp3 V0 Extreme. They both sound very good.
Does anyone know if Windows Media Player will allow aac files in a playlist? Does Windows Media Player organize music in folders by artist?