Greg,

Here is one of our Oracle systems that is used for data entry,
accounting, inventory, and various reporting tasks like sales analysis
and stock reports.

RS/6000 p550, 8 GB Memory, 4 processors

This was designed to hold a max of 180 users and is running 6 instances
(2 production, 2 training, 2 month-end reporting). It seems to be
running Oracle 9.2 well at the present time.

Our production init.ora file had these settings if it helps at all. I'm
not an Oracle DBA so could not tell you if these will work well for
you. But it may give you something to compare to.

db_files = 80
db_file_multiblock_read_count = 1000
db_block_buffers = 45000
db_block_size=4096
shared_pool_size = 300000000
log_checkpoint_interval = 10000
processes=600
parallel_max_servers = 16
log_buffer=64000
timed_statistics=false
max_dump_file_size = 10240
transactions = 200
transactions_per_rollback_segment = 40
open_cursors=2500
optimizer_index_caching=50
dml_locks=90000