it depends on what was on the drive and where it's going.
If you only have data that's of minimal threat to you if released into the wild and you're giving the drive to your nephew, zero out is more than enough.
If you're selling a drive that used to contain highly sensitive data and it's going to an eBay purchaser in Nigeria, I'd probably opt for 7-pass.
As an aside: When I worked in the defense contracting environment, I learned that marketing claims about multiple zero out passes meeting DoD government standards were largely baseless: every secret project I worked on required that when the project was over, the drives be pulled from our macs and destroyed under the eyes of a government auditor. The macs were then sold without drives in them.