A few easy things that you might like to check first are,
Check the wireless card is on on the laptop(on laptops this is usually turned on and off by holding the function key down and pressing one of the F keys) and the router has wireless connections enabled.
Check that the wireless router is broadcasting the SSID, it can be difficult to configure if its not.
What security are you running on the wireless connection, ie WEP? Try turning all wireless security off until you have it configured.
Right click the My Computer icon and then device manager to see if there are any unknown devices or any exclamation marks.
Sorry just re-read your question, if the laptop is picking up your friends wireless connection but not yours I think the problem is more to do with your router than the laptop. If you can give me the make I will have a look.
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