[pneff]

Newbie to backup procedures and technology. Bought a 1 tb, Western Digital, USB external backup for my year-old iMac using latest OS X. Backed up the internal drive and it takes up about 175 GB space on the new drive. My question, can I use the remaining space on the external drive for things like keeping iMovie 09 event footage? Can I just specify to iMovie to place the footage on the external drive or do I need to do something to the external drive first? Partition? If I need to partition does the backup that is already there get erased so that I must re backup into one of the new partitions? Any help would be greatly appreciated.