I recently had a similar problem where I could import pyodbc at the python shell, but I was getting a DLL error when I tried to import pyodbc under mod_wsgi. I suggest that you put "import pyodbc" inside your wsgihandler.py (or at the top of db.py) and see what errors are being produced. I had recently had this problem and resolved it by following the steps described here: http://code.google.com/p/pyodbc/issues/detail?id=214
Chris Guest