... with Eraser I just get the option to erase and I'm not sure how many times it's overwriting the file. I really want to make sure my files get really deleted so how many passes does Eraser make? Thanks.
With Eraser you in fact have a large number of different erasing methods to choose from, and (should you be so minded) you can even set up your own. Assuming you are using Eraser 6 (version 6.0.7 is the current stable version that most users should choose), the settings dialogue is where you change the default Erasing method. But you can also choose the method to use for any task you set up. All of this is explained in the necessary detail in the PDF Help file you can open from within the program.
The default erasing methods for files and folders are Gutmann (35 pass) for erasing files and folders and single pass pseudorandom data overwrite for free space on disk. The latter is only single pass because anything else takes too long on all but the smallest drives. Current thinking is that even a single pass erase of a more modern drive is sufficient to make the overwritten data irrecoverable for all practical purposes. Gutmann is definitely overkill on modern drives (even Peter Gutmann says so), but is implemented as the default for files/folders because many users who are unaware of the latest thinking want nothing less.