Dear,
You can start MOSS 2007 development by using its objec model.

1- For this purpose you must have visual studio 2005 or above on your machine.
2- Kindly download the MOSS 2007 SDK from microsoft site.
    It contains lot of sample development and how to's in it.

MOSS 2007 SDK Link
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http://msdn2.microsoft.com/en-us/library/ms550992.aspx

Happy Starting :)



Regards,
Tariq Younas
Software Engineer
INTECH PROCESS AUTOMATIONS