Yeah, getting a wifi card should work. Once you find a wifi network to connect to, you'll be online and free to check email, browse the 'net, etc.
To search for wifi hotspots, I suggest that you google for "wififofum." It's a great finder, and if you have GPS, even better - it'll tell ya exactly where a connection is (as long as there's enough signal strength to reach the PDA/phone. However, if you're no where near a wifi hotspot, you're out of luck for the Internet, unless you get a data plan of some sort.