Asia - Sri Lanka Tour Guides?

Hello,
I will be visiting Sri Lanka at the end of this month, February, for a week long trip.
Is it always best to go with a local tour guide for the trips? I understand it's pretty much impossible to do it without a guide.
Does anyone have any recommendations for tour guides and contact information?
Thanks so much!

We used Jetwing (http://www.jetwing.com/l) for a trip we took 4 years or so ago. They quoted the itinerary that I supplied. We had a car and driver for our tour of the historic interior of the country. It was extremely well done.

We are headed to Sri Lanka for the first time at the end of this month as well. I contacted a few ground agents, and ended up going with a travel planner we had used in India several years ago. She then coordinated our trip with a ground agent in Sri Lanka. Of course we can't comment on the quality, but we have been pleased thus far and have a knock out itinerary planned. If you want her contact info please PM me.

Thanks for your suggestions!