using the difference function

Hi,

I am new to PostgreSQL but have a strong background is MS SQL Server.

I am trying to use the difference function within embedded sql using
Npsql.

I receive the following error:

Error: 42883: function difference(text, text) does not exist.

A bit of googling shows me that the difference function is part of a
fuzzystrmatch module.
I have installed PostgreSQL 8.3 using a windows exe. Looking under
C:\Program Files\PostgreSQL\8.3\lib i can see fuzzystrmatch.dll.
However it is not in the bin folder.
Is this function considered a bolt-on to PostgreSQL and if so:
1. How do I install it?
2. Does it install to the server or to each database?
Best regards
Phil Smith

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