How Many Sites Can I Run – One Installation

Mac 10.7.5
MAMP 2.1.1
PHP 5.4.4

localhost:8888/wordpress – works great.

Issue – I have three themes to preview for a client – not just one, how can I set them up as individual sites?

maybe like:
localhost:8888/wordpress_1
localhost:8888/wordpress_2

etc…

(I named my only db wp_1 with the expectation of adding more sites)

is MAMP Pro the simple answer?

Thanks much – 🙂