Scalability of postgresql.

I am about to embark on a development project for my company. I am
concerned with Scalibility. I am looking for someone that has/is using
postgres in a production environment with a scale that is similar to
what I am describing below. I would like to know what type of hardware
and access methods these companies are using. For example, are you
using JDBC or some native drivers. Is it web based or client server.
Is anyone using the cygwin stuff in a large scale environment.

Thanks in advance for any insights anyone has.

I am developing an application that will have approximately 200 tables.
Many of these tables will have in the order of 20,000 rows. 10 or so
tables will have over 1,000,000 records.

Access to this system will be client server using a JAVA Swing
application. There will be some access using a servlet/jsp engine
(shopping cart type app). There may be as many as 100-150 connections
to the database at any given time.

What would be the RAM requirement for the database server?

Is this too large for Postgres?

Any input would be appreciated.

Thanks,

mark