[GonzaloGil]

SmarterStats uses the log files to get visitor data, while Google analytics uses cookies and javascript (that snippet you entered in the page). So, if customer has javascript turned off, or no cookies, then Google won't track.

However, if that was the case, they probably wouldnt be shopping either. So, as far as bandwidth reports, etc, i would look at smarterstats, but as far as real visitors, (real people not spiders, robots, etc.), the Google counts are very accurate.