What state do you live in?
Check out Erie Insurance. www.erieinsurance.com. I know they're not all over the states, though.. so check out if they have it in your state.
I'm an insurance agent so do tons of quotes a day. The cheapest companies for someone with a clean record is Erie, State Farm, Farmers. Erie has a lot of discounts for having a squeaky clean record.

Check around your area to different agents and get quotes!
They're free! What harm can it do?
If you do switch, just make sure they are matching the coverages. A lot of times I came across this in the business where they drop some coverages in order to give you a better price. (this happens mostly with companies that you go direct with. IE, Geico, Progressive, Liberty Mutual)
Good luck!