ODBC to Oracle (data source name not found)

[Michael J. Moore]

I have set up an ODBC connection to an oracle database named MIKE on my
local machine. I have tested this ODBC connection using EXCEL and it works
fine. The same data source results in ...
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Python 2.2.3 (#42, May 30 2003, 18:12:08) [MSC 32 bit (Intel)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> import dbi
>>> import odbc
>>> d=odbc.odbc('mike/mike/guess')
Traceback (most recent call last):
  File "<stdin>", line 1, in ?
dbi.operation-error: [Microsoft][ODBC Driver Manager] Data source name not
found
 and no default driver specified in LOGIN
>>>


What am I not doing correctly?
TIA Mike