I require a program that can take albums or files from an iTunes library (from AIFF or WAV), compress them to AAC and copy them to an iPod. Using iTunes, this process entails first making a copy of the files in AAC format before syncing. This then leaves my library with two copies of each album I have synced (one in AIFF and one in AAC format). I need the process to be done on the fly, either in RAM (preferably) or deleting temporary AAC files from the hard disk as it goes. The program can interface with iTunes if this is considered the best way. Initially, the program is needed to operate on Mac OS-X, but if it could be adapted to operate on Windows later, that would be preferable.