please help me with my toshiba laptop

Hi,
I have bought a new Toshiba Satelite M205-S3217 laptop and i do have a Lantech Wireless Router with me. the wireless adapter is Atheros AR5007EG Wireless Adapter
Windows Vista Home Premium is the operating system in the Laptop
when i try to connect it to the router it shows that Network Connections are Available but when i connect it does not connect and it says try re-connecting again.
i tried several times but it did not connects.
i have a PDA with me which has a wireless Lan as well and it connects easily to my Router and even to Laptop through Adhoc Connection. but the Laptop does not connects to Router?
i have tried to keep a WEP Key security as well but it shows the same problem.
i am completely blank of what to do as we do not have any support center here in Nepal.
please do kindly help me with it.
i would be highly obliged.
my direct email is kooldude_r@hotmail.com
will await for your kind help
Ritesh