odbc is a way of coonnecting to various different database types, and the only way you can connect to MS Acess using php.
To connect to it you will need to have the server admin create a DSN for the database...you can't simply have php read and write to the database without one of these. Once you have the DSN set up you cannot move the database.
ASP lets you connect to a MS access DB without a DSN otherwise known as a DSNless connection...juts like reading a file, but if you are using php then you cannot do this an dare stuck with the DSN way.
Have aread of the odbc features in the php manual.
scottd