My intention is to partition an external HD in half allowing it to serve as a backup for a pc running windows xp, and the other half as a backup for a mac(10.5. I am using a Seagate external HD(new) that was initially partitioned on a windows xp computer.The 1st half of the 1TB HD was formatted in NTFS format, and the second half was erased and (I thought) reformatted in HFS plus but when I attempt to use CCC(Carbon Copy) to copy the mac 1/2 of the hard drive, I get this message: "You may have difficulty booting from this target volume, the underlying disk is not formatted with a partitioning scheme that Apple recommends for Intel Macs." I have read the recommendations that the external HD need to be partitioned with APM or GPT, but I cannot seem to get to that option now for the mac side of the external HD. In the Disk Utility, the external HD shows both sections of the partitioned drive(the xp section and the leopard). I do not want to reformat the entire drive(both sections) if at all possible. I just want the Mac side of the ext drive to be properly prepared for CCC, and the windows side to remain as is. Any suggestions would be appreciated.