The thing you need to remember about calories in alcohol is that they are "empty" calories and not stored by the body.
The reason why alcohol makes you gain weight is that the body 'likes' it because it is easy to utilise and so it uses up the alcohol calories first and stores the food calories. Think about it ..............
..... have you ever seen a fat alcoholic (i.e. someone who is properly alcohol dependent, not a 'functioning alcoholic')? They always look emaciated inspite of the fact that they consume thousands of alcohol calories every day.
..... have you every seen a fat 'it girl' (I'm not talking about your common or garden 'celeb' or WAG but people like Paris Hilton)? Inspite of drinking gallons of champagne etc they remain slim because they don't eat. Look at Amy Winehouse - she drinks but doesn't eat, unlike Jade Goody and Kerry Katona.
So it's not just about how many calories you drink, it's also about how many food calories you consume.