Are you trying an Ad Hoc ( direct wireless NIC to wireless NIC) connection, or an infrastructure mode (wireless NIC to wireless router) connection?
In short the details of your network are unknown.
I'm trying to set up wireless internet for my laptop (Compaq Presario 722, Windows XP Home) to my parents Dell which is connected to a modem. I bought a Netgear MA521, and followed the procedures to install to the letter.It says works w/ XP... But... I absolutely cannot get my internet to work. The signal strength is decent, about 74%, and the LED's are lit up. I tried to configure the TCP/IP manually - I didn't know which IP's to use - When I did ipconfig, it didn't show a default gateway.
Let me know if you need more info -- I'm sure I left something important out, I'm so frazzled.
Thanks so much!!

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