The best way is to discover who the drive manufacturer is, then go to their website and download the drive utility. Then create a boot disk of the utility and run low-level format from inside it. Most my drives are Maxtor, so I use their utility call PowereMax. I have downloaded similar utilities from other manufacturers as well.

Barring that, I have also successfully done low level formats by tyipng in some code at the command prompt. Its supposed to work on all drives regardless of manufacturer. I can't find the link with the code though, so go with the disk utility.

I always low level format before allowing a computer to be culled. Within the office however a regular format is good enough.