Building a click-tracking app in PHP and using PostgreSQL... heard it's better than MySQL for large number of transactions...

Was wondering if there a was a guideline or a way to find out what hardware would be needed..?

Example....

RAM needed = (nbr_queries(SELECT)/min * 15) + (nub_queries(INSERT or UPDATE)/min * 10)
CPU needed = [...same...]

Just need help to know what kind of hardware I need for my application, depending on the nbr of queries and on the number visitors executing the php at the same time.

Thx.

....gb