Mike,
I would first recommend that you take some classes to become familiarized with SQL Server. I would be happy to recommend a quality training center to you, or some books.
Second, their is a way for SQL Server to link tables. It is called Linked Servers. In your SQL code you would refer to them by Servername.databasename.owner.tablename
By I5 I presume you are referring to the system formerly known as iSeries, formerly known as AS/400, and that it is in DB2.
I have user SQL Server to interface with an iSeries before. We loaded Client access 32 on the SQL Server and then we were able to set up connectivity. In that case we used DTS to copy data back and forth. But you could also use linked servers.
David Lundell
Principal Consultant and Trainer
www.mutuallybeneficial.com