Temporary disappointement in salary :-(

Since my date of joining was on 17th july 2008 i thought that i'll be paid on 1st 1st aug 2008 .i.e for 14 days.All guys in my batch also thought the same .But to our disappointment the HR told that we will only be paid on 1st sep 2008.Because the salary calculations would be from 15th of one month to 15th of next month.Since we joined 17th we were unlucky.But they told that we would get salary for 45 days in next month.So friends if you join before 15th of month then you are lucky to get that months salary.Regarding salary we are not sure on take home pay , we'll know only we get in our hands.But it must be approx 17 to 18(not sure).