A. A. There are a variety of methods/tools :-

1. For MS-Access you can try the free Access upsizing wizards available from MS's website - check out the softlib area under www.microsoft.com/support. These will convert from versions of Access to SQL 4.x, 6.x and 7.x.
Try http://www.microsoft.com/accessdev/prodinfo/aut97dat.htm and
http://support.microsoft.com/support/downloads/dp2864.asp?FR=0
for more info.

2. If you can unload the data from the foreign dbms into flat-file format - e.g. tab separated, comma-separated, fixed-format etc. then you can use the SQL BCP.EXE tool. This is a command-line program and is fully doc'd in the books-online. It is the fastest way of getting data into/out of SQL Server, but it only works via flat-files. The unload and load processes have to happen in series - meaning longer run times.

3. If you have an ODBC driver for the other format then there are several 3rd party tools you can use that offer transfer/migration functionality and are gui-based, but can also be automated and run from the command-line. These tools can be used to copy to/from ANY ODBC data sources - they don't have to be SQL Server at one end. Examples of these sorts of tools are :-

www.datajunction.com (Data Junction)
www.sqlmover.com (SQL Mover)
www.platinum.com (InfoPump)

4. If you have SQL 7.0 then this comes with a tool called DTS that works in a similar manner to the above. It works with any Odbc or OLE-DB accessible data source. Again it doesn't have to be SQL 7.0 at one end. However if you weren't using it to migrate to/from SQL 7.0 you would have to check whether there were any licensing implications.

5. Specifically for the AS/400 there are a couple of tools that have been around for some time - offering real-time replication as well as transfer.

www.datamirror.com (Data Mirror). DataMirror will bi-directionally replicate between AS/400, SQL Server, Oracle, Sybase and DB/2.
www.visionsolutions.com (Symbiator)

For generic ODBC/OLE-DB access to the AS/400 also see

www.hit.com/hitweb/daccess/dchome.htm

Whatever you use you still need a driver to connect to the AS/400 that works - here is one that is reported to work ok with SQL 6.5 and 7.0.
IBM's Client Access ODBC driver v3.1.3 SP48155

6. Oracle has a Migration Workbench utility for free download. Search
www.oracle.com for "Migration Workbench".