I've read that Time Machine will back up mac journaled formated external drives, unless you exclude them. That's all well and good, but my situation is a little different. Here's my setup. 15" MBP, 120GB HDD AEBS RAID 0 1TB WD My Book Pro II drive on the network as an airport disk. 500 GB WD Pro drive on firewire 800. The 500 gig is going to be used as my time machine drive. The 1TB Airport Disk drive is mostly media. The only thing I want backed up is some important document folders as well as my music folder. But when I go to exclude the folders I don't want backedup on my 1TB airport disk drive, I find that the entire contents of the drive isn't selectable to be excluded. I don't really have any space on my internal drive to store these files. All drives are mac journal extended formatted.