Don't confuse a domain and hosting. The hosting is where you keep your files and a host will most likely have server-side languages and databases supported, the domain is just the name that people type to get to your site.
For example, my web-host is dreamhost.com but I registered my domain name at godaddy.com. All I had to do was point the domain to the dreamhost name servers.
I don't know where you can buy .nl domains from, however there is a sticky thread in this forum about web-hosts.