Here's a big joke amoungst us techies:

Q: Who's the biggest wireless ISP?
A: Linksys

What is really meant here is that so many home users are installing wireless routers (Linksys being one of the most popular) with absolutely no security...which then enables anyone within 100-200 feet of your home (e.g.: parked in the cul-de-sac) to jack into your wireless router and surf the Internet using YOUR connection...or worse yet to monitor all your communications. In my own personal experiences, I find that 50-75% of the access points I encounter to be unsecured...great for us, very bad for you.

Here are the specific risks you expose yourself to when you fail to secure your Wireless router:

Solution: Enable WPA (WiFi Protected Access) on your router AND all computers connected to it