i got a 1380 in GRE- 660(verbal) and 720(math)..need advice.

hey..
i am doing engineering in computers currently studying in 6th semester....i gave my GRE on the 19th..i wish to pursue a MS in MIS....

i got 1380 in GRE with a split up of 660 in verbal and 720 in maths...my preparation was decent and i wasnt expecting anything less than 1400...

but the real mess up happened when i lost track of time in my math paper and had to fluke my last 6-8 answers because of which i think i ended up with a score of 720 only.. i know it's below average and that's why i am planning to give my GRE again...

if i end up with a 770 or lesser in math in my second attempt at GRE and say my verbal score decreases by a few points i would end up getting a 1410 or 1420 which would just be a jump of 40 marks at the most... that's why i am confused and i would really appreciate if you could help me out with some questions i have ... :-

1)How do good universities(say top 25-30) treat a student with a second attempt? which score is considered? the average or the latest?

2)How bad is a score of 720 in math for a student like me who wishes to pursue a MS in MIS with a really good academic background in school and junior college and an aggregate of something more than 65% in engineering school? what are my chances of getting a good university with my current score?

3)Does a percentile matter?

4)what if i get a 770 or lesser in maths in my second attempt? will it worsen my case?

..any kinda help will be great....