Needing some serious help with netbooks and wireless internet please!?

Right this is probably gonna be a long question lol. I got sky broadband put in on friday the 1st of April this year. I personally own an Advent Roma 2000, Windows 7 etc I know my computer like the back of my hand. My mum has a an Acer Aspire 1 netbook, Windows Xp. Now bakc to my advent, I set up the wireless connection in a matter of minutes and am currently experiencing no issues whatsoever, internet speeds are great! But, my mums netbook is a different stroy. It definitley has a wireless on which is located at the front of the netbook and it is enabled. It says I am connected to my router but I can't browse the internet. Everytime I click google.co.uk for example, I'll get the 'internet explorer is experiencing connections difficulties' error. It's starting to really frustrate my mum because I moaned at her for ages to get Sky broadband cause i like how fast it is etc she's angry enough with the crap picture the hd box is giving out. Seems to be one thing after another. I would really appreciate some thorough help cause its a nightmare! I've got 3 internet dongles that I've tried connecting to the router with but it doesnt work either! thanks in advance.