Insulation, Radiant and Vapor Barriers - Solid Walls!

Upon doing some renovation on my Cape, I discovered the exterior walls to be solid wood. About 3.5" thick, 5" high posts layed horizontally on top of one another, notched out like tongue and groove. They sit almost like a log cabin. I was insulating with 3/4" ferring strips on the inside and placing styrofoam boards in between followed by a vapor barrieer. Is this worth it? The R value of the foam is around 5. Is the wood good enough insulation?

According to: http://www.eere.energy.gov/consumer/your_home/designing_remodeling/index.cfm/mytopic=10170

"The R-value for wood ranges between 1.41 per inch (2.54 cm) for most softwoods and 0.71 for most hardwoods. Ignoring the benefits of the thermal mass, a 6-inch (15.24 cm) thick log wall would have a clear-wall (a wall without windows or doors) R-value of just over 8."

Thanks for the info. I guess every little "R" helps!