Replying to Xbox 360/wireless help

Right now im trying to hook up my 360 to my wireless internet that i just bought and hooked up.  The xbox says that there is no network connection and out of the choices it gave me of what could be wrong, the only possibility could me that it is out of range.  I get internet on my laptop in my room where i never used to, but the 360 wont pick up a signal.  I Have a belkin G router and the xbox brand antena that i bought for 100 bucks.  The only thing i can possibly think of why it wont connect is the antenea isnt powerful enough. Any suggestions?