Wireless Signal/Router Problems

Hi, I have a new Mac Book with the 2.16ghz 2 gb ram etc which has a strange problem when on the wireless airport. When I use the laptop in my lounge via airport I have to put the MB in a particular spot to get a signal, if I sit with it on my lap it doesn't work but if I place it on a particular spot on my coffee table it works perfect.

If I go upstairs it work fine it's just in around my lounge so it's very strange, I don't think my walls are lead lined or anything is being broadcast, if anyone has come across the same problem or a similar problem please let me know.

As far as I know if works perfect everywhere else, the only thing I have in the lounge that broadcast any signal is a cordless phone.

Any help would be appreciated.

Cheers

Lee