Calculating maximum number of concurrent database connections

Hi Drupal friends!

I hope this is the place to post this question. If it is not, please accept my apologizes.

I am changing my hosting provider due to a problem; I have a blog implemented in Drupal 6 that has traffic peaks of approx 500 visitors at the same time. When it happens, I get the famous error "Too many connections".

What I have right now is:
Linux Centos
PHP5 , MySQL 5 Apache 2
1Gb RAM

I would like to be sure that the new server will support these traffic peaks.
And now the question:
Is there a way to calculate the needed resources to have a specific number of concurrent connections to my database?
Is there a software to simulate this situation?

Thanks in advance.

Cheers.
Diego.