Your co-worker is speaking on matters he has almost zero knowledge about. Maybe the best description is when grandmother tries to convince you that the CD-ROM is really a cup holder which tucks back inside the computer.
As for Centrino being more network capable and being easier to hack into--I say BS. Hacking is also the wrong term (when you write a program, it is said that you are hacking (i.e. writting, making-it-work, etc.) the source code). I think he meant "cracking" which is the equivalent of forced entry in the computer world. Cracking cannot happen unless you have an operating system on the laptop. The chip itself, if sitting on a table, can't really be hacked. Maybe he was refering to the fact that Centrino notebooks come with wireless connections which are said to be insecure. The problem is, Centrino notebooks are not the only ones with wireless connections. Most of the sager notebooks can be had with desktop P4's and wireless so using your co-workers logic, P4's are easily hackable.
Bottom line is this, any time a computer has access to it from a modem, wired (ethernet) network card, wireless network card, infrared, bluetooth, etc. the machine has an entry point. The only secure computer system is one that is off and locked away where no one can get to it. Think about it like this, if your house has windows, then it can be burglarized easier because a theif could break them and come inside. If it doesn't have windows but a solid concrete wall, it'll be harder. But what if the theif didn't know where your house was or couldn't get to it? It's even more secure then. I hope that makes sense.