inspiron 1520 wireless card question

Hello, I am looking to purchase an Inspiron 1520 for college in the fall but have a few questions on the wireless card options.  I would like the Draft N card but there is a footnote that says that the Intel Mini Card N will only work with a 5x router or something along those lines.  Does this mean that if I don't have a Draft N router the card will not work at all or just not at N speeds and range ?  If I go with the Inspiron 1521 it comes with a dell wireless N card and says nothing about not working with specific routers! ????  Can someone explain in detail.