select the files in iTunes and, from the
advanced menu, choose +create MP3 version+.
edit: just noticed you're on iTunes 8 so it might be different in that version. see this KB article:
http://support.apple.com/kb/ht1550.
alternatively, use one of
these free apps to convert the wav's before adding to your library.
J
GG
edited by the Jolly
Green Giant (where
Green stands for environmentally friendly)