W-8BEN is actually for NRA's who are subject to 30% withholding on FDAP income or claim treaty rates or exemptions for US tax withholding purposes. W-9, on the other hand, is to certify US status, generally, to avoid backup withholdings. Foreign vendors accept both, depending on whether the taxpayer is an NRA or a US person 
Just one more reason it's good to have you around here....sometimes I know *just* enough to get in trouble
We tag team here (somehow, I keep seeing WWF in my head as I type this although that's really not what I mean) 
