You have right to return to USA even if you have 1 day US visa on your passport. I had returned back to USA even  I had just  a couple of  months visa on my passport. So, don't worry about it. You can also apply for  F1 visa extension in US Embassy with all the necessary documentation. Since you still have valid visa until January 2010, it's upto the Embassy if you could get visa extension or not. Good luck if you want to try.