Performance issues

Hi,

I am running Postgresql 8.4.7 with Postgis 2.0 (for raster support).
Server is mainly 1 user for spatial data processing. This involves queries
that can take hours.

This is running on a ubuntu 10.10 Server with Core2Duo 6600 @ 2.4 GHZ, 6 GB
RAM.

My postgresql.conf:
# - Memory -
shared_buffers = 1024MB # min 128kB
# (change requires restart)
temp_buffers = 256MB # min 800kB
#max_prepared_transactions = 0 # zero disables the feature
# (change requires restart)
# Note: Increasing max_prepared_transactions costs ~600 bytes of shared
memory
# per transaction slot, plus lock space (see max_locks_per_transaction).
# It is not advisable to set max_prepared_transactions nonzero unless you
# actively intend to use prepared transactions.
work_mem = 1024MB # min 64kB
maintenance_work_mem = 256MB # min 1MB
max_stack_depth = 7MB # min 100kB
wal_buffers = 8MB
effective_cache_size = 3072MB

Everything else is default.

My Pgbench results:
/usr/lib/postgresql/8.4/bin/pgbench -T 60 test1
starting vacuum...end.
transaction type: TPC-B (sort of)
scaling factor: 1
query mode: simple
number of clients: 1
duration: 60 s
number of transactions actually processed: 7004
tps = 116.728199 (including connections establishing)
tps = 116.733012 (excluding connections establishing)

My question is if these are acceptable results, or if someone can recommend
settings which will improve my servers performance.

Andreas