The Washington Post has a good article by Alan S. Kay on wireless home or office WiFi networks entitled "WiFi Promise Vs. Reality".

WiFi signals weaken not just over distance but also as they pass through physical objects such as walls, ceilings and fireplaces. In our tests, those obstructions outweighed distance in attenuating a WiFi signal. When the connection gets sufficiently weak -- in our tests, 20 percent of the original strength -- the WiFi hardware will give up on it.

Kay used an old big frame house and found that 2 walls, a floor, and 25 feet of distance were enough to cause WiFi signals to fail. One could compensate for this partially by placing the base station in the center of the house. But the center might not be a convenient location.

WiFi is faster than any standard web connection. So the bandwidth it supplies is sufficient for allowing one to web surf anywhere in a house. But if one wants to do heavy file sharing with large files moving between client boxes and servers it is going to be a lot slower than 100 Mbps ethernet.

The coolest effect of WiFi is probably in public places. Coffee shops, hotels, and other businesses are using WiFi to provide internet access to customers.

Cho, the owner of Murky Coffee, said he never considered charging for WiFi. He said he recoups the $70-a-month cost through coffee and sandwich sales.

"What this has been able to do is bring in people in the evening, and they buy a cup of coffee," Cho said. "I figure, if you're savvy enough to use it, then you're probably savvy enough to . . . find a different connection for free."

Security holes in WiFi put privacy at risk.

You can limit your risk by changing passwords regularly, making your WiFi network invisible to strangers, lowering its signal strength to keep it from escaping your house, and restricting addresses to designated computers, as identified by their unique hardware addresses.

The fixes for the security holes are not present in old hardware.

Developers of WiFi hardware returned to the lab and came up with a better system of encryption called WPA, for "WiFi Protected Access," which implements a much more robust system for securing an 802.11 network of any kind, a, b or g

If you start using WiFi you have another security risk to worry about. If building a new home it still seems worth it to properly cable the place. Keep in mind that the bandwidth for wireless is inadequate for high bandwidth video applications. If you want to be best set up for the future seriously consider putting in fiber optic cabling. The fiber optic NICs are kinda pricey but at about $100 to $600 not enormously so. If you are going to go to the trouble to run cables thru walls and floors then putting in fiber optics is probably worth it. Gigabit thru-put would support even HDTV quality video signals. You could even put video cameras in rooms tied to the fiber optic network for security purposes.