If you make a website availeble in multible languages then you should make the domain nl.domain.com instead of domain.com/nl.
Its better for Google :aggressive:
Why is nl.domain.com better than domain.com/nl? I have used the latter on my site and from what I remember Matt Cutts saying there shouldn't be that much of a difference anymore.
You are all wrong about google and SEO. It doesn't care about domain names or subdomains. Its all about meta tag words. Thats its and that is all. All the rest relies on your content in keeping visitors coming to increase ranks.