802.11n problem in mac/pc

I’ve just bought an imac 20″ Core2Duo computer. I’m trying to use both pc and mac together. In mac part, I can easily connect via wireless , but in a pc part it is not connecting via new Broadcom 802.11n wireless adapter.Could it be update problem or something else..pc giving a message of cannot getting an IP address… Help needed…I have same config on a another mac book core 2duo bought last year and have a atheros wireless adapter..No problems occured in mac/pc parts..