Like I a said, there are many things that cause interference, but only if you let them interfere!

The first thing and most important thing while setting up your network is to see what else is around you. On the computer with the wifi card, search for local networks and see what networks are available and write down their channels. When setting up your router, make sure you are not on the same channel as someone else! It does not matter at this point what channel you are on.

The second thing is to see what other wireless devices are in the area, this includes things like cordless phones, 2-way radios, microwaves, many remote controls, and many that you won't even know about! Try to figure out what is all in the area that you know of though, if you live in a densely populated area or apartment building this will be very hard.

The next thing to watch for is building materials. In a recent install I just did, the computer room was on an outer "wing" of the house which was surrounded by brick, the router was upstairs, and it had probably 20 walls, floors, and stairs to go through! Even with a small amplifier and 15db gain antenna we could not get signal - in a case like this sometimes you just have to add an access point and run a cable - even if it doesn't look the best. If you are concerned about looks, you can actually buy molding to run wire through. The other thing to remember is that going through a wall perpendicular (directly through) will only "look" about 6" thick, at a 45 degree angle it "looks" 6ft. thick! and at 2 degrees it looks to be 42" thick! Try to make the straightest connection possible to the workstations (computers). Things like brick walls, metal studs, or going through at an angle will all cut down your signal dramatically!

One more thing, when trying to increase signal throughout a large area, multiple floors, or even from house to house, there are many possibilities. The first and most important thing in my opinion is a good Name Brand antenna - watch out for these homemade antennas, or if you see a 15db gain antenna for $30 it's not real! A real 15db gain antenna will cost around $300 (10X the price!). DLink, Linksys, Netgear, Belkin, and Cisco are all good name brands. Make sure that each device has a good antenna, and read the specs on the antenna - you see there is no such thing as a true "omnidirectional" antenna. It may broadcast 360 degrees around, but only transmit 15 to 30 degrees up and down. Knowing your antenna, you may now position it so that it is "aiming" at the other antenna. Do the same to the other antenna. Finally, if you must go through floors, or have dead spots in the house, an access point can be very helpful, place the router in the most central point of the house, and place access points throughout the house at the edge of your wireless network. An access point will pickup the signal from your router and computer and "repeat" it. Just make sure that the access point you are buying acts as a repeater as well. DO NOT buy that "range extedender" from Linksys! It is junk, my personal favorites for AP's, well any equipment is DLink.

Finally, if you have tried all of the above, and no matter what can not get signal due to interference in the 2.4Ghz range, you may buy 802.11A products instead. Currently there are 3 standards and 1 substandard. I'll explain below:

802.11B - 2.4Ghz / max speed 11Mbps / max distance 300ft

802.11G - 2.4Ghz / max speed 54Mbps / max distance 300ft

802.11A - 5.8Ghz / max speed 54Mbps / max distance 150ft

Wifi N Draft - 2.4Ghz / max speed 300-400Mbps / max distance up to 12x further than B or G

The new N has no official standards, may or may not work with other hardware, may have further distance or may have less distance, etc etc - Since there is no standard from the 802.1x committy NO ONE KNOWS!

The max distances listed are very accurate according to the 802.1x commity, I hate to say it but range booster routers, and 108G is all false advertising, all a range booster may have a slighly bigger antenna (1 or 2db) but nothing worth paying extra money for! Save your money and do it right!