sole proprietor (Canada based) needs assistance with IRS W8

[gimminy]

Hello,

I'm self employed in Canada (sole proprietor) and I have some U.S. based clients. I was informed that my U.S. clients were suppose to withhold 30% of all $ paid becuase I didn't have a US employer ID or US tax ID.

I'm a bit lost at what to do. One of the forms that I think I need to fill out is W-8BEN, but even with this I'm not sure exactly what needs to get filled out, and I want to be able to be totally excempt from having any monies withheld.

Do I need to get a US tax ID, and would there be any other forms needed to fill out?

Thx!