I was wondering, is it possible to make a wireless LAN without using a Switch or an access point. Because all of my frens have laptop and a centrino built. So we would like to play together wirelessly and probably file sharing. Do u think this is possible?

You can use a wireless Router - Then you would only need a NIC card for either your desktop or your laptop. Where you your friends get their internet from? Centrino is built into the laptop so they don't require a network card.

It is possible. You want to set your Wifi cards to ad hoc mode, not infrastructure. However, all your PC's must be in range of each other to work. I would recommend a wireless router though. It works better and it's a heck of a lot easier to secure, share net connections, and setup in general. MCSE, MCSA Messaging, baby!