Question : Wireless Network Interference

Very small wireless network in a retail space using Netgear FM114P and Netgear MA101 adaptors. There is interference casuing the wireless network connection between the adaptors and router to drop.  Sometimes it will work fine for days, other times it will fail hourly (but works more often than not).  Unfortunately the store is using a 2.4 GHz telephone (Panasonic) and there are two wireless LANs that can be seen in the vicinity.  Workstations running XP Pro SP1.

Per Netgear, I have used the Netgear utility to configure  instead of the XP utility.  Have setTx rate to 5.5 and set to short preamble.  Using short WEP keys.  I have tried every channel, some work worse than others, but all exhibit problems.  I have repositioned the wireless router for oiptimal reception.  I have considered recommending that the telephone be replaced, but since they are using 2-line phone, 5.8 GHz models are out and 900MHz models are missing features they want.

First, am I missing any solution to make this current setup work?  There are no FCC approved boosters or antennas for these products.

Second, what are my alternatives?  
Copper is my last choice, the space does not lend itself to a retrofit.  It's doable if it's the only way, but expensive and "messy".  

I briefly considered 802.11a, but I'm concerned about distance (this is not a huge space, but it is my understanding that it can be as short as 50-100 feet, which would be a problem).

Now I'm considering PowerPlug adaptors (Netgear XE102).  However, Netgear does not "recommend" them in business environments.  Anyone have any experieinces with them?

Answer : Wireless Network Interference

I also would stay away from the "PowerPlug" adapters. Industrial/commercial environment circuits tend to be very noisy, and even if it works you're unlikely to get decent bandwidth.

You're operating in a largely unregulated spectrum. If there's interference, then you sound like you've already taken every reasonable action to correct it. Its doubtful you can do much more.

If you suspect the phone, then you need to ask them which they want more - a working LAN or certain phone features. That will drive your decision on how to continue.

If they are willing to give up the phone features to switch to 900 MHz, then the problem may be solved. If it still isn't solved, they can always switch back to 2.4 GHz, can't they?

If they regard the phone as more important that the working LAN, I'd suggest falling back to your last resort and running a hardline, as its obvious the environment is too noisy, RF-wise, for a WLAN.