All those sequential scans: 6 million from a total of 32 million page reads.
Are you *sure* you ran update stats?

Also, although you say you could use up to 3GBytes of memory for the
database server, you're actually using less than 1 Gbyte, and your buffer
cache ("Yes, we speak Oracle!") is only about half a gig in size. Still,
your cache rates are pretty good nonetheless ....
--
Neil Truby t:01932 724027
Director m:07798 811708
Ardenta Limited e:neil.truby@ardenta.com