My concern has always been someone using my Wi-Fi for illegal activity, such as downloading music/movies illegally, or driving around the neighborhood in a van using other people's wi-fi connections to download child pornography (register.com) Yes, that guy got caught, but if he hadn't, the owners of that Wi-Fi account would be the first to take the blame.

There's a difference between merely broadcasting the SSID and leaving the router at factory defaults. My neighbor's SSID is linksys, and his username/password is admin/admin. I could see every single setting in his router and could have changed it all, had I wanted to. The problem is that Linksys routers are too damn hard for mere mortals to configure. They are enormously complex with lots of wireless jargon like SSID, WPA, etc...

By the way, you misspelled Windows.

I leave my wireless network open. Like a good user concerned with security, I check my logs regularly. When I find someone attempting to attack one of the machines on my network, I block their MAC address. Simple, yes, and while it might not be able to stand up to the most sophisticated of attackers, that's really not so important to me.

I like being able to access the Internet at coffee shops and at random from my car. I would hate to see that privilege go away because of the slim threat of criminal use and the inconvenience that might temporarily cause me. If someone uses my network to download child porn, or even illegal MP3s, they're not doing so with my consent. Paranoia over the chance of such misuse coupled with possible misunderstanding by law enforcement isn't enough to keep me from offering open access.

(But I do block everything but http and https for bandwidth purposes)

Bruce Schneier mentioned this once on his blog.

I used to like the idea of leaving my network open. At the time, when I scanned for networks in my area I would only see 1 or 2. Now, however, when I allow my wirless card to search for networks I can see 6 or 8! Most of them have a default SSID (linksys) and no encryption. With that many networks around (and hence that many users) it becomes much more likely for someone to accidentally piggyback on your connection. ("Your trusted networks cannot be found. Join the discovered network linksys?") While this may not be a bad thing, I for one like to have good bandwidth. My uploads, downloads, sf.net updates/commits, etc go very fast. If 5 of my neighbors hop on my exposed network... well, that goes downhill fast.