Do domain name extensions matter when optmalizing for a certain language?
 

Let's say I want to attract dutch speaking surfers only. Does it matter if I use a .com/.net extension or would I be getting better results using a .nl/.be extension?

I'd say .nl/be, i use geo targeted UK domains as most UK directories only accept .co.uk etc, plus international listings.

Kind of best of both worlds if that makes sense.

I'm pretty sure it will work in your advantage!

If you decide to go .com, you need the domain on a Beligan IP. Walmart, for example, bought a .com, put it on a UK domain and SEOd the hell out of it to rank #1 under a month for "car insurance" in UK local.

That's a competitive term, so it proves their decision not to bother with a .co.uk TLD wasn't a bad one. If you want to play it safe I say go with a .be and put it on a Belgian IP. I wouldn't think of those factors as ranking boosters though; they help Google decide whether or not to include you in local searches. So if you got a .be domain on a BE IP that's not necessarily going to help you outrank a .com on a BE IP or a .be on a US IP.

Why did Walmart optimize for UK traffic? According to Google Trends, more people from the UK than US search for "car insurance."