Approval letter of PhD study

Just now I got the approval letter from Waikato University through email, and hopefully I'll receive the original letter tomorrow. Now then I'll have to consider my VISA thing as the Immigration has been marked as a trouble maker by many (including me). So far everything is basically under my control. But I'm not sure if there'll be any trouble in the Immigration. Since my enrolment will be from Sep/1/2005 and there're some more time for me to "struggle" the Immigration thing (1 month should be enough! ...I hope), I still hope that any strange problem (like the X-Ray issues happened last year) would not happen any more.