Dreamhost PS - Configuration question

I was looking DreamHost PS (http://www.dreamhostps.com/) and through
support they said that a minimum (good) configuration will be 300/300
(300mhz of CPU and 300mb of RAM).

I'll run my app over mongrel. My app is a small to medium application.
Is this configuration enough or I should get more (or maybe less)? In
my projection, I will have about 4.000 visits this month.

Details of my app: It is a products indexer, it crawles some webpages
and displays the results in a nicer (I hope =) way. I'm using a cache
of one day for any dynamic page. The app can be visited here, if you
wish: http://www.taperas.com/

There are no complex queries (to mysql) and I'm using ferret. (I'm not
using the DRb server, I just search the index files).