DBAN
I've never used 'anti forensic' tools. I've done a forensics module back in uni and I can say it's a difficult to properly erase data. Most of the 'formatting' tools just remove the pointer from you OS to the HDD.
Fully encrypt your HDD (preferably with a huge password, 16-20 chars) install Linux, be happy :P
DBAN is good for mechanical drives that contain platters and store data via logical block addressing; however, this will not work for Solid-State Drives (SSD) as they use a different technology to store data. The SSD's use NAND. The data ( 0's and 1's) stored in a SSD is stored in an array that looks like a grid with 0's and 1's while a mechanical drive stores the 0's and 1's in sectors on a drive platter.
There are many zero-fill utilities that can do the job for both, but essentially you are filling in all data with 0's. It is best to check using a HeX editor; this will verify that all zero's have been written to the storage device.
I have a few other tricks, but I am keeping that to myself.
@Mordak Definitely Ironic… but not spying on you just yet, leaving that up to the NSA for now.. tee-hee