Postgresql Performance on an HP DL385 and SmartArray 642

I am do some consulting for an animal hospital in the Boston, MA area.
They wanted a new server to run their database on. The client wants
everything from one vendor, they wanted Dell initially, I'd advised
against it. I recommended a dual Opteron system from either Sun or HP.
They settled on a DL385 8GB of RAM with two disc U320 SCSI and a 6-disc
U320 SCSI array. I recommended they add a RAID adapter with at 128MB and
battery backup, they added a HP SmartArray 642 to connect to the drive
array in addition to the SmartArray 6i which came with the server.

Has anyone worked with server before. I've read the SmartArray 6i is a
poor performer, I wonder if the SmartArray 642 adapter would have the
same fate?

The database data is on the drive array(RAID10) and the pg_xlog is on
the internal RAID1 on the 6i controller. The results have been poor.

My guess is the controllers are garbage.

Thanks for any advice.

Steve Poe