RAID for the DB filesystem

Hi,
my database is hit with constant inserts to 6 main tables (200 inserts
per minute to one of the tables, less to the others), some updates,
but then the selects:
- large retrievals of randomly different sections of the database
(indexed maps by postgis). This data is static.
- medium sized retrievals of the same tables that are receiving the
inserts. By mediou sized, I mean typically 200 rows at once. These
retrievals are also randomly different to each other, and typically
retrieving the newly inserted data rather than the more historical.
The database size is about 300GB and growing.

What sort of hardware config would you advise?
I'm thinking of 2x300GB SATA RAID 0 for the OS and application files,
and 6x300GB SAS RAID 10 for the database... but some experts have said
RAID 5 is fine. I'm inlined to think RAID 10, but I'm not an expert.
Your advice will be much appreciated.
Thanks
Brian
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