This is especially true if you come from an area with a high denial rate. If there is any question about whether you have been a serious student, this can quickly answer the counsul's questions. A letter of good standing from the University is almost never required. Under the 1996 immigration act, nonimmigrants who violate their legal status in the U.S. may obtain new visas only in their home countries. Be prepared for a closer scrutiny of your application as well as several days processing time in the consulate.
Special rules apply to obtaining a U.S. visa in Canada or Mexico.
See the special handout on that process.