The minimum marks require to qualify AIEEE examination according to 2011 are following.
For Gen category : 48 marks
For OBC category : 45 marks
For ST/SC or PH : 18 marks.
So the qualifying marks this year will be somewhere around this figure only. Although the AIEEE changed its pattern of examination, qualifying marks and the seats are increased in past few years many a times. Thus it is hard to say the exact qualifying will be same or not. But for sure they will be around this figure. Also to get in NITs you need to score exceptional well as the minimum marks will make you eligible for AIEEE counselling but not for NITs. The competition is high. So be prepared for it. Make a list of preferred colleges and lock the best college in counselling.