minimum hardware requirements for small postgres db

I am having difficulty finding documentation stating the minimum hardware
requirements to run pg under Windows. (I did look in the FAQ & User Manual)

I seek an open source RDBMS with close adherance to ANSI standards, good
free graphic design tools for drawing of the ER Diagram, validation of the
ERD model, and generation of the SQL required to build the DB.

I only want to design a few small DB Apps using about 20 tables, for
single-user offline environment, hopefully runnable on Nettop class
hardware under WinXP or Win7 32bit.

I want to access the db via a Forms driven GUI and a Report-writer with
features comparable to old versions of Access, but preferably also
open-source.

If Atom class nettop not sufficient, would like to know the minimum class
of CPU, RAM, GPU required.

Thank you in advance for any assistance