I had my visa renewed on March 31 2008 (after about a yr of expiration) and I got stamped until 2013 March 30. Some of my fren went and got there and got their renewed (they were like 8 of them and all of them got their visas). But here's the catch however, a friend of mine got his about a month ago (at this times his visa had already been expired for 5 yrs). He got only for 1 yr (I 20 duration) and he said he had to stop about 5 hrs at PoE because he said the lady at PoE said she had to do some background check since she said he looked like Mexican).

They basically give u visa for the period of  your current I20. Do not listen to rumors. Do not have any criminal backgrounds, have good academic standings, buckle up, and go ahead with the process. you will get it.