I've made my decision, BUT!

I've decided to buy the 15.4" MBP. But ofcourse I want to be able to surf wireless in and around our house. What do I have to buy to do this?

The MacBook Pro has wireless built in.

Or do you mean a wireless router?

If so, I'd recommend Apple's AirPort Extreme.

I guess that's what I mean. And all I have to do then is plug the internet cable in that Airport Extreme?
Edit:
I just found all the information on the Apple site, silly me -_-.

lol i do the same but i have a netgear router. i think im going to have 2 get a airport my old router is on it way out.

It depends on your connection; I wouldn't advise anyone to with an ADSL connection to get an Airport Extreme... any benefits of buying an Apple product are cruelly ripped away when you have to tack-on a 3rd party modem.

Get a Netgear Gateway Wireless Router. It's cheap and has everything you need (modem+router).

Well, maybe it's a bit more complicated.
We've already got a router (us robotics), so what do I do...?