Security & Signal Interference W/wireless Mac-airport Express


I'm by no means a techie.
In my home we are using the Airport Express for wireless connection to my iBook G4 and to a desk top iMac G5 (w/Airport card), both are running Tiger OS 10.4.2. We set up using the Airport asst. and needed to call Apple for help to reset it when a PC family user was "helping us" to get connected and he "crashed it" (we couldn't receive an Internet signal which we think was the Airport doing it's job - security wise). Anyway, we also lost a signal on both systems for an afternoon even though the A.P. Express station had it's constant green light (which means it should work). We went into network assts. or something & got set up again. But Apple wasn't all that helpful in answering ?'s regarding security. Both units have only the network we created listed (which is a closed network) but I'm still wondering about phishing/hackers etc. because we do a lot of on-line shopping. Apple claims our Airport should have no detectable signal to a phisher.
Also, the Airport went out (no black bars on either unit) again the other day & was back up on it's own later. We have only 900MHz phones, no baby monitors. But the new neighbors have an electric guitar and amp? I'm assuming. (I've heard guitar amps can interfere.) Their house is close to the wall where A.P. Express is installed but these homes are 80 yrs. old, the walls are thick and probably plaster. Could something in their home mess up our signal & do we need firewall software? Sorry so wordy. Many thanks for any advice.

Yes, it is quite possible that something like the guitar amp could interfere. Even if the amp itself is a good distance away, it will be drawing a lot of current, and there's a good chance the power supply cabling runs through the wall and causes interference.

My first recommendation is that you try turning on the "Interference Robustness" mode of te airport express, which you can do by going into Applications/Utilities/Airport Administrator. You may also try moving the airport station, sometimes relocating it as little as a metre away from where it is will fix the problem.

As for your questions about security:
- Signals travelling between your Macs and your Airport Express are, by defualt, encrypted using WEP or wireless encryption protocol. Even if they were intercepted, which would only be possible if the hacker was actually within range of the station, they would require military-grade code-breaking to actually decrypt the information.
- Mac OS X includes firewall software, built in. You can set it up in System Preferences --> Sharing --> Firewall.
- A "phishing" attack is still a concern. These are typically setup as a fake email sent to your email address, claiming to be from a legitimate source, asking you to confirm credit card details or some other valuable piece of information. The email will have a link that goes to a fake site, setup purely to harvest this information. The rule is: NEVER put you personal details into a site that you got to by following a lonk in your email. In fact, I'd rule out ever going to a link in your email.
If you do get such a request from your bank or ebay or something, it will always address you by name, and ask you to browse to the site MANUALLY.