performance issues

Hello all,
We are running 7.0.3 on a RH 7.0 box w/twin 733 pentium CPUs, 512 meg.
ram and a 3 drive raid 5 scsi array. The machine is dedicated. Our main
table is about 700,000 rows with an associated table of about 15,000
rows.
-N 128 -B 256
logging to a file
Without spelling out our complete schema I'll give some basic info
main table has 37 columns with 3 indexes, several foreign key
constraints and one rule
the associated table has about 10 columns all or which are int 4 with
the exception of one text
Most of our queries are simple select queries, half of which would use
the indexes.
Now, does this scenario sound about right or do I have a lot of work to
do?
At any given moment having 12 - 16 queries running (say 1 update & one
insert, the rest selects),
I'm dragging bad. Vacuum -z was just run. top gives me numbers around
20. Even with just a 2 or 3 queries running top gives me 2 - 3. Does
this sound typical?
If my information is insufficient to give a ballpark quess, perhaps you
could give me some normal types of performance figures.

Thank you for your feedback.
--
Bill MacArthur
Webmaster
DHS Club