Augeas, you must understand that no secure file deletion method is foolproof. With the right amount of time, a data recovery expert, and the right softwware and hardware combination, any data can be recovered. The only way to permanently erase your data is to use very strong magnets and move them around on the disk. Then, melt the hard drive platters at a very high heat temperature, Then, smash the disk into little pieces, and throw it in the garbage.
I use Gutmann's 35 pass file deletion method, it's incredibly secure, but sometimes the Windows file deletion skips certain other files if you use this method.