Access 97/Postgres migration

Hi there,

we are considering using Postgres as our new backend DB. But we have a rather complicated Access application which we
needto migrate. The idea is to export all the tables from Access to Postgres, then  
link them back using ODBC so that the Access interface will remain untouched.
I just wonder how it would work with the auto_increment data type of Access, I've read that Postgres has the data type
"Serial"but it doesn't seem that I can insert a value into it because it should be  
generated automatically. Now the problem is how can I convert the existing IDs (primary key) to serial?
And would this setup work well at all? Is there anything I should keep in mind from the beginning?
Any hints or tips would be highly appreciated, and many thanks in advance!

regards
ZHU Jia