Performance Tuning / RAM Usage

I am running postgresql 7.1.2 on redhat 7.2 and having problems with
performance... During peak activity, the postgres processes lock up and
report "UPDATE waiting" (under ps listing) with no light at the end of the
tunnel.

There is a script which has to insert up to a couple hundred new records
into two large (800,000 record each) tables, and the inserts take well over
a minute. I don't mind it taking time, but I'm concerned when the processes
start failing all together!

I have 512M of RAM on a 1Ghz PIII server (Dell), and all database
connections are made through php. They are all persistent connections.

I am considering adding 1536M of additional RAM (for a grand total of 2G)
and possibly updating to redhat 7.3 (with postgres 7.2) if necessary.

I am really looking to find the best way to configure the database to
utilize the existing RAM (and any new RAM I may add). Also, to what degree
will adding memory help the database performance if the select and insert
operations are mostly disk-intensive?

Thanks,
Garo Hussenjian.

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