Autovacuum Tuning advice

I have a very busy system that takes about 9 million inserts per day and each record gets updated at least once after the insert (all for the one same table), there are other tables that get hit but not as severely. As suspected I am having a problem with table bloat. Any advice on how to be more aggressive with autovacuum? I am using 8.4.1. My machine has 4 Intel Xeon 3000 MHz Processors with 8 GB of Ram.

Currently I am using only defaults for autovac.

shared_buffers = 768MB # min 128kB
work_mem = 1MB # min 64kB
maintenance_work_mem = 384MB

#------------------------------------------------------------------------------
# AUTOVACUUM PARAMETERS
#------------------------------------------------------------------------------
#autovacuum = on

#log_autovacuum_min_duration = -1

#autovacuum_max_workers = 3
#autovacuum_naptime = 1min
#autovacuum_vacuum_threshold = 50

#autovacuum_analyze_threshold = 50

#autovacuum_vacuum_scale_factor = 0.2
#autovacuum_analyze_scale_factor = 0.1
#autovacuum_freeze_max_age = 200000000

#autovacuum_vacuum_cost_delay = 20ms

#autovacuum_vacuum_cost_limit = -1