Default_with_oids

I recently went from Postgres 7.4.8 to 8.2.1 (Linux Platform).

After conversion I noticed my forms created with the utility PGACCESS
failed.  I found since then that PGACCESS requires oids to perform as I
used it prior to the conversion.  If I set "default_with_oids = true"
then the forms work in 8.2.1.

My questions:

Why is "default_with_oids =false" the default in 8.2.1 ?  Does the use
of oids effect database performance?  Is "default_with_oids" set per
server, database, or by table?


Thank you.

--
Joanne R. Salerno