Database Design Question - Mailing list pgsql-general

A Question for those of you who consider yourself crack Database Designers.

I am currently moving a large database(100+Tables) into pgSQL... with the intention of deploying against 'any' SQL
databasein the future. The development side will be rigorously using Standard SQL constructs with no unique/proprietary
extensions.

My question concerns establishing the relationships.

Currently Relationships between tables are established via a Unique Integer ID like this:

*=APrimaryKey

 PartTypes    Customer     Parts
 ---------    --------     -----
 PartTypeID   CustomerID   PartID
*PartType    *Customer     PartTypeID
              Address      CustomerID
                          *PartNumber(2FieldPrimaryKey)
                          *PartRevision(2FieldPrimaryKey)
                           PartName


HOWEVER; I have read lots of texts describing the Relational Design should be instead like this:

*=APrimaryKey

 PartTypes    Customer     Parts
 ---------    --------     -----
*PartType    *Customer     PartType
              Address     *PartNumber(2FieldPrimaryKey)
                          *PartRevison(2FieldPrimaryKey)
                           PartName
                           Customer

Both Techniques have a unique foreign key back to the parent tables but one uses No.Meaningful.Info.Integer.Data for
theForeignKey while the second uses Human.Understandable.ForeignKeys 

Is one recommended over the other??? Sure appreciate the commentary before I get in too deep with all these tables.

Thanks!