WordPress 3.0.x installs on 1and1 servers pretty much as documented in the standard installation instructions found here.
In fact, the Famous 5-Minute Install steps found on this page work great but start the 1and1 MySQL db creation now if you want to have a chance of completing it inside of five minutes.
However, you will want to insert the php5 related entries in your .htaccess file as described in some of my other 1and1 related posts and here.
Create a file in the home directory of your site called .htaccess with the lines:
AddType x-mapp-php5 .php
AddHandler x-mapp-php5 .php