Scaling further up

All:

We have a Quad-Intel XEON 2.0GHz (1MB cache), 12GB memory, running RH9,
PG 7.4.0. There's an internal U320, 10K RPM RAID-10 setup on 4 drives.

We are expecting a pretty high load, a few thousands of 'concurrent'
users executing either select, insert, update, statments.

What is the next step up in terms of handling very heavy loads?
Clustering?

Are there any standard, recommended clustering options?

How about this? http://c-jdbc.objectweb.org
<http://c-jdbc.objectweb.org>

Also, in terms of hardware, overall, what benefits more, a SunFire 880
(6 or 8 CPUs, lots of RAM, internal FC Drives) type of machine, or an
IA-64 architecture?

Appreciate any inputs,

Thanks,
Anjan
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