Need help choosing a wireless card

I'm trying to decide between between the the Intel Pro/wireless 3945 a/g or Dell draft n wireless. I'm not planning on getting a wireless router or subscribing to any sort of wireless internet because I'm only going to use my notebook away from home when I'm at school. Do you have to have your own internet subscription or can you just get a notebook with a wireless card and use it. For example, I have a friend who doesn't pay for internet, but he gets internet on his notebook in his apartment. Is this because someone in the apartment has a wireless router and his notebook is just picking up its signal.

From what I understand there are usually areas throughout the city, such as hotels, restaurants, etc. that offer free wireless connection. If this is the case, do both these cards work in those areas? I thought I read somewhere you have to have a certain type router for the draft n wireless. Do they both work off of different signals? and if so, which one is stronger, and more common? Which do you think will work best for how i'll be using it?

Thanks. As you can tell, I know very little about this subject, so you help is greatly appreciated.

 

So basically the Wifi card will allow me to access the internet for free in certain areas where a business, or a college might offer a wireless network as a service to their customers. Is their a way to tell if you are using the network of one of these business and not "stealing" from an unsuspecting neighbor? Also, do you know if it will be possible to upgrade your wireless card to n when the standards are set?