Get the model number and make of the laptop and look to see what it supports, if the card is built in. If the card is an add on, then just the make and model number of the card is needed.
BTW: just because the WIFI support on the laptop may be g or n does not mean it will connect that way. The router or "hot spot" must also support the connection type.
I use XP , how can I know which verison of WIFI , b ,g or n does the wireless lan card support in the notebook???