MySQL - PostgreSQL - DB2 - What?

[Tomàs Núñez Lirola <tomas@grupoeon.net>]

Hi
We're planning a new website where we will use a DB with 500.000 to 1.000.000 
records. We are now deciding which database server we will use. We've read 
that MySQL has big problems from 150.000 records and more. Also we've read 
that PostgreSQL is very slow on such records.
But we don't have any experience, so we must rely on other people experience.

I'm sure there are some stories about DB servers, like MySQL being the fastest 
ever, or MySQL functionality being the most ridiculous ever (can't do certain 
subselects, triggers...).

What do you think of that stories? Which DB server would you use?