Wi-Fi security

I was recently reminded of the importance of maintaining a secure Internet environment when using Wi-Fi at home. I was having breakfast with a close friend this past Memorial Day, and he inquired about how I had set up my wireless access at home. The reason is that he has wireless set up at his place, but every once in a while when he fires up his computer, he would be connecting to another router (he would notice this from the indicator by his system clock). He still connects fine, but worries about how secure his own router is - that someone can hack in and mess it up. He also didn't like the idea that someone could be leeching off of his wireless connection that he's paying good money for. I told him I'd stop by later to check it out, but I remember I had to deal with that when we first set up our wireless connection at our condo. Being that we were in a condo, anyone upstairs, downstairs, and across the hall could tap into our router if they had a wireless card in their computer. But since the people in the condo complex at that time were elderly, retired people, there was no reason to act on anything. However, a younger couple later moved in next door, and soon enough I noticed wireless activity on my router at a time when I was sure our computers were turned off. At that time, I decided to filter out all wireless card access except for the ones I specifically allowed access. That apparently did the trick, and haven't had a problem since. Security is an important issue, and it's always good to stay on top of things to avoid getting burned. Ironically, every once in a while I still can access other wireless routers when I do a scan of the area from our condo (as other people have jumped on the wireless bandwagon by now)...