Most new lapotps will come with internal WiFi, which isn't something you swap out, as it's part of the computer.
As far as a computer, if all you want is something to run DeLorme on, you don't need an expensive computer. Pretty much anything you buy will run it. I'd recommend NOT buying one from a store, and customize it online, so as not to get something you don't need. You can buy one online, without many extra features you may or may not want, for less than $600.
www.hpshopping.com
www.dell.com