What chipset is it based on? It is very likely that there is no Linux driver for your wlan card, and one of the main reasons is that there is really no 802.11g standard yet. The linux-wlan project has a list of adapters
where the chipset for each adapter is listed, but yours doesn't seem to be there (yet).
One thing you could try, if you are willing to part with some money, is trying the Linuxant
driver loader. It uses the Windows driver to get the card going under Linux, but it is not free software.