I came across this very slick method for deleting duplicate records while poking around on StackOverflow today.  I've used a variety of methods in the past for deleting dupes, but nothing quite as clean as this.

The SQL below would work for a table in the following format, you'll need to adjust as necessary.  Please note that this will only work if id is a Primary key.

MyTable: id, Col1, Col2, Col3

And the SQL:

DELETE MyTable 
FROM MyTable
LEFT OUTER JOIN (
   SELECT MIN(id) as id, Col1, Col2, Col3 
   FROM MyTable 
   GROUP BY Col1, Col2, Col3
) as KeepRows ON
   MyTable.id= KeepRows.id
WHERE
   KeepRows.id IS NULL

Hope this helps someone!