Design question - OLAP

I have no d/b design experience so please bear with me on this.
I have been charged with setting up a d/b for use with Cognos Powerplay & Impromptu.
Data is coming from a mainframe, I'm using DTS to pump this to SQL7.
The source is a circulation database. I'm looking to link 30+ magazine tables to a single email table.
Mag_Tables contain 91 varchar fields(Pub_Code,Sub_ID,etc...)
EMAIL contains (Pub_Code,Sub_ID,Email_Address).

The Sub_ID field is not unique between Mag_Tables , so I was thinking of creating a
concatenated PK on Pub_Code & Sub_ID for both tables. Is this recommended?

Do I need to link these tables within SQLServer? One of our Access people is telling me I need
to create a join on the PK.
Thanks for any advice.