Garry:
You said It very well. I went with contractors insurance, instead of lanscapers. The landscapers insurance was to defined as to what was covered and what was not. Contractors ins. seems to run about 15% to 20%higher than landscapers ins. If you go with contractors you may want to sit down with your agent and define some parameters of what your doing and what will be covered. Otherwise they will write you a blanket policy, and those can be quite expensive. They will also try to factor in depreciation schedules for your equipment. These schedules are usually provided by them are quite unrealistic for most small operators. Be firm about what sort of hours, wear,etc you expect out of your equipment. Or they might only pay off a fraction of its value. If your only doing random jobs once in a while its really hard to put a value on just how much to carry. Just remember that with your customers the skies the limit when it comes to their imagination. Several times I have been amazed at how some twenty year old damage finds its way onto a claim. You might talk to any other small operators in your area to find out who covers them and for how much.
Check into your states requirements to see if you need a contractors license also. If your just part timeing it, you may be able to find a general to carry you as a subcontrator under their license.