Depends on what you are trying to protect from. Quick erase will be sufficient to keep any forensic software programs from recovering any data.
There are hardware methods that can still "see" past the quick erase method. This would require opening the drive, connecting several thousand dollars worth of equipment to the drive electronics, having the proper "almost clean-room" environment to keep from damaging the disk, and a lot of skill and knowledge about the drive itself.
Not something your local neighborhood hacker is capable of... unless he also happens to be an electrical engineering student with access to a university lab. In this case, he will be too busy to care about whats on your hard drive.
