VS 2005 Identifying "duplicate" Street Addresses?

The problem at hand is to search an Access database for "duplicate" street addresses, given user input of street address, city, state, and zip code.Given the zip code, city and state do not need to be looked at.

My thought was to select off records in the database with the zip code that matches the input, then loop through those records, performing a "similarity" test on the street address field as compared to the input street address. Obviously we cannot test for exact matches (i.e. "SW" vs. "South West", etc.). This problem has obviously been solved before with post office software, algorithms used by mapping applications, etc.

But do you have any thoughts on what algorithm I might implement in a VB 2005 app?