server install recommendations?

hi everybody:

in a couple of days i will reinstall an offline database server. It's
a old HP Proliant DL580 G3 with three disks (147 GB each). Currently
it has a debian Sarge in a RAID5 hardware array ( with HP Smart Array
6i, [RAID bus controller: Compaq Computer Corporation Smart Array 64xx
(rev 01)] ).

i googled a while and get to this page:
http://www.powerpostgresql.com/PerfList , so my first question is,
this document and the tips given hasn't been deprecated by now, right?

then:
-is raid5 the worst election in this scenario (three disks)?
-which is the best (and with that i mean secure in first place and
with more perfomance in second) possible configuration achievable with
this three disks?
-should i ask my boss to buy another disk? (it will be difficult, but
if i can demonstrate It worth it...)

i think i will "Separate the Transaction Log from the Database" with
two RAID1 arrays (if they buy the new disk). is this a good way to go?
it would be too bad if i put the logs in a disk without RAID? (only if
i dont get the new disk...)

our application (running on separate webserver) is of the type "OLTP",
the server will be entirely dedicated to postgresql. i will configure
a warm-standby server, so the WAL files will be forwarded to another
server.

thanks in advance!

--
Roberto Scattini
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