This is a short but important post. Part of a photographer's "behind the scenes job" is to back-up, archive and catalog every image he shoots for his clients.
This is a great article (and video) describing how one photographer handles backing up his work. This process may seem a bit excessive, but it's a good, safe approach. At our shop, we charge between $75 – $350 per job.
Remember, none of your equipment, software or time is free, so charge for it!