How do I undo an import??

[Tom]

I'm a C++ programmer, new to Python, working with v1.5.2 on Windows.

I run the command-line interpreter, then I type:

>>> from NetCfg import *

to import my extension.  Now I want to unload my NetCfg DLL without exiting
the interpreter.  How do I do this?

Also, I type the above import command every time I start the interpreter.
Is there some way to get have this command executed automatically?

Thanks,

Tom.