I'm also assuming you're installing a single blog and not Wordpress MU. Who is hosting the site? They should be able to help you through it if not install it for you - and a lot of them have scripts that do it automagically.
As the server is configured with Plesk I assume PHP/MySQL etc. is working and the web server is Apache, not IIS.
Is the 'server configuration error' an HTTP error response ie 'Error 500 Server Configuration Error', not something that looks like it comes from WordPress (been a while since I did a WordPress install)?