@Steve Davies 3
"Yes, the WIFI is hackable BUT can an unauthorised device connect to the Interweb once you have hacked the WEP password?
Well, not in my case, as my router is setup to ONLY allow know MAC addresses to actually connect."
Short answer: Yes, they can, Steve - and even on your network...
Any decent hacker worth their salt could, once they've decrypted your WEP password, sniff for your MAC address and clone it - easy as pie to do on Linux.
If they wanted to make things even more interesting for you, they could use a second wireless card with another MAC address - and deliberately poison your ARP cache, so that instead of sending traffic out to your router, it instead gets proxied through their notebook and out through their cloned MAC address, which of course, your router will accept, since it has no way of knowing the difference between a real MAC address and a cloned one.
Having someone snooping (and easily modifying what you do online) is worrying enough, but here's more: If they can manage to snaffle a certificate on to your machine (trojan, worm, other flaw in your OS or browser - and don't assume they're all published or patched), then they pretty much own your connection - even if you think you're protected with SSL. Result: Next time you bank online, it could cost more than you bargained for.
MAC address protection is actually no protection at all, since MAC addresses can easily be cloned very easily - and since you need to broadcast yours with any information you send, it gives an attacker all the information they need to impersonate you. MAC address protection might impress your friends - provided they know sweet FA about networking, that is - but the first real criminal who wants to sign on and use your network connection to do evil will, I'm afraid, be able to overcome such protection in less than 30 seconds.
Use WPA2. If your router doesn't support this, go out and buy one that does. If you can find a device that can detect ARP attack attempts, so much the better. Choose a password that can't be guessed easily, and I do hope you're not using a wireless keyboard...