Wireless problem on dell mini Inspiron ( wont hold connection)

TO whom it may concern,

I recently bought a dell inspiron mini laptop. It was running great for first 3 months when suddenly the wireless failed. I have tried many things to no avail. It detects networks but failes to gold connection endlessly trying to connect to isp to no avail. I rang Dell who told me that it was a software problem and not covered under waranty and would fix for a fee of 80 euros. I have tried many things but still wont work. i have windows xp as os even disabled the dell wireless manger and used microsofts wireless manger whick worked initially but since no joy! any help welcomed from this technologically inapt user.

Mnay thanks in advance for any help :)