thanks Sparty for the reply. I do know that fact. I am planing to travel across canada, which entails leaving the US territory and re-entering. Any idea if that will be a problem after expiration of visa ?

 Jogee, yes, of course it will be a problem if your visa is expired. Even though you have a valid I20 but if you're visa is expired, they might not allow you to enter U.S according to the USCIS website. But until and unless you have a valid I20 and valid visa, doesn't matter how many days or month left, they should allow you to enter U.S. If i were you, i would take suggestion with my school international advisor/DSO. 

i sought suggestion from my advisor and she mentioned that it, technically, should not be a problem. But i thought it would be a wise idea to seek advise/stories from people who might have gone through similar situation. I want to make sure i can come back without any hassle. I appreciate you taking time to answer my question.

If you travel to Canada (only Canada and not other countries) and reenter US within 30 days, you should be fine. One of my friends did the same and she was fine. But you may wanna check with your International advisor.

 Jogee,it's a good idea to seek suggestion from our own people here in sajha but let me tell you one thing that you get whole bunch of different thoughts and ideas from different people which might be good and bad, so if it turn out to be bad, what will you do? So that's the problem you might face here in sajha let's hope for the best and good luck for the trip. Don't forget to go to Niagara falls :-)

thanks dreamsboulevard. I am rather new to sajha community, so I appreciate your comment. I am not much interested in eastern provinces, i will be traveling across BC and Alberta, and my be sasketchewan. As they say, West is the Best :)

 You're most definitely welcome sir/mam :-)

 I think the term is "automatic visa revalidation". Search for that term.
(eg: http://www.ohr.wisc.edu/ifss/AutomaticVisaRevalidation.htm)
Cheers!