I am a semi-pro photographer. All of my RAW files are 8-12MB each. Each weekend I shoot 2-3 hundred shots, keep about 100 or so. Processed images are 20-60MB each. 10,000 + mp3 files, 3 powerbooks with 60GB drives, all 2/3 full. And its just me and my wife. So far we occupy over 350GB of data...