Steves Art Gallery........On this page you have to look for Negative Meta balls. I beleive you have to hold the shift key when selecting the metaball Icon, this will make it "negative".

Link to this site is also in the List I put together for the Backroom / Links.
Check the top thread here in the forum. (soon will be posted in the header)

___
Ockham's razor- It's that simple