On Mon, 26 Nov 2007 10:38:47 -0800 (PST),
wrote:

Walls are R11 with an extra inch of styrofoam and
housewrap under the siding.

That's your problem. The walls should be R30. The insulation
effectiveness (ie reducing heat loss) graph plot rises steeply from
zero to R30 then flattens off. That is beyond R30 you won't realise
much more insulation gain. But R 11 is certainly pretty low on
insulation effectiveness.