If required, I use a wipe program accross HDD's that will do 6 passes. This is available free of charge on the Ultimate Bott CD's. The Department of Defence here request the HDD out of all copiers and they do their own wiping on the HDD. If any data can be recovered once the wipe program is finished, then the HDD is used as target practice out on the range. lol
Stirton, I came accross any interesting fact the other day with on a security camera training course. In the US, it is illegal to have encryption with anything greater than 128 bit. The reason being that anything greater than 128 bit requires more processing power and time for the CIA to decrypt. So I would presume that NSA and CIA would use something like 256 or 512 bit encryption. Just a useless fact that I learnt.