wireless internet

I have a DELL Inspiron 1150 laptop which I use in the UK & in France. In the UK I use a netgear router which works wireless with my PC but I have to use an ethernet line to get the DELL online.
In France I use an ORANGE LIVEBOX but the problem is the same the DELL will not get to the internet wirelessly but will connect using the ethernet line.
Any idea what the problem is?
Is it just an old farty problem!!!!
(using wINDOWS XP)