Hardware for PostgreSQL

I am trying to build a very Robust DB server that will support 1000+
concurrent users (all ready have seen max of 237 no pooling being
used). I have read so many articles now that I am just saturated. I
have a general idea but would like feedback from others.

I understand query tuning and table design play a large role in
performance, but taking that factor away
and focusing on just hardware, what is the best hardware to get for Pg
to work at the highest level
(meaning speed at returning results)?

How does pg utilize multiple processors? The more the better?
Are queries spread across multiple processors?
Is Pg 64 bit?
If so what processors are recommended?

I read this : http://www.postgresql.org/files/documentation/books/aw_pgsql/hw_performance/node12.html
POSTGRESQL uses a multi-process model, meaning each database
connection has its own Unix process. Because of this, all multi-cpu
operating systems can spread multiple database connections among the
available CPUs. However, if only a single database connection is
active, it can only use one CPU. POSTGRESQL does not use multi-
threading to allow a single process to use multiple CPUs.

Its pretty old (2003) but is it still accurate? if this statement is
accurate how would it affect connection pooling software like pg_pool?

RAM? The more the merrier right? Understanding shmmax and the pg
config file parameters for shared mem has to be adjusted to use it.
Disks? standard Raid rules right? 1 for safety 5 for best mix of
performance and safety?
Any preference of SCSI over SATA? What about using a High speed (fibre
channel) mass storage device?

Who has built the biggest baddest Pg server out there and what do you
use?

Thanks!