Sounds like you have a likin fer little 'uns .... the Feds are coming...you are going to jail mr paedo! Garry Glitter got captured when he took his pc into pc world and the i.t. guy saw the 'goods' stored on his hard drive ....game over for Glitter Balls!
Delete the folders, then run Eraser and chose the option to "wipe tips"... that's the left over data on sectors not completely written over by current programs/data. If you want to keep the OS intact, you'll need to use some software which claims to unrecoverably erase/overwrite data. Eraser can go one step further and erase ALL the tips and overwrite all sectors not currently occupied with your programs. Or, you could use a Low Level Format utility to wipe the drive, then reinstall the OS.
So you are saying use Eraser and choose the overwrite cluster tips option How do I tell Eraser to overwrite all unused space/sectors or is this automatically done after erasing a folder I select? Thanks.
If protecting your data is that important, why rely on software that "probably" will work? Swap out the drive. If you can't afford the 50 bucks to do this, then it doesn't sound like it's really that important. If you want to save the data, you've got it. If you want it destroyed, then destroy the old disk. One good whack out in the street with a 10# sledge ought to do it.
Once you delete folders, the sectors they occupied become "unused space" as far as the MFT is concerned... and Eraser is supposed to overwrite that space when you choose that option.
I've used Eraser when selling or donating a computer. I don't KNOW for sure that it's doing what it says, but you can see it indicate it's making multiple passes. You can chose 1, 3, 7, 35 passes... maybe some other choices.... can be an overnight job on a big hard drive.