Oh, you poor thing. I can sympathize.. I *know* your pain. The attached picture was taken Oct 10, 2005, less than 2 months after I bought my house.. and I bought it because it had two mature trees in the back yard. But digging up arbor vitae isn't that bad, they don't have THAT bad of a root ball. Actually, if there's any way possible, rent a bobcat (they have little bitty ones that are like 3' wide) and you can grub up the rootsystem pretty easily.. I had that done last year w/some old juniper stumps. I had to dig up some roses to prevent them from getting run over, but it was SOOO worth it rather than the backbreaking work of trying to dig it up by hand. Maybe *Maybe* you can take down the fence & bribe your neighbor somehow to allowing the bobcat to go through via his side? Or, even renting a skidsteer would be better!
Or some M80s planted in a row around the stumps... :D
