permanant file removal good or bad?

ok I've never used the eraser program before so i was wondering if it is good to have your hard disc written over so much to permanently get rid of files?

does it have any negative effects on the computer or its longevity?

 

Nah, disks are being written/overwritten constantly, just looks at your paging file. I have a 2GB partition just for my page file and the disk is just peachy.

 

I actually have never understood this....if you need to write over files multiple times to actually get rid of them, what is on the HD when it has been written over once?

Theoretically if you can write a file over the top of another and still recover the old file our hard discs have a much larger capacity then stated!!

I understand that a file may be marked as unused and only gets written over when something is used in that actualy physical space but cant understand how after being written over physically it is still there.