Well it depends on what you mean by internal wireless. Some computers come with a mini-pci based wifi adapter. Others have it built into the chipset.
Just need to buy a new mini-pci wifi card to get 802.11g if you have a b adapter in the slot (generally on the bottom of the computer, small slot 2 1.5 inches square with a screw in it)... however if it's built into the chipset, need to get a PCMCIA card or you can get a mini-pci card if you have a slot in your computer.
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