Can I end a sentence with a preposition?
Yes, you may definitely end a sentence with a preposition, when appropriate. There is no such rule against it anymore. I have worked in the professional world of publishing before I became interested in education, and so I am perhaps more aware of changes that have happened to the English language in the past few decades. It is an obsolete rule that was based on Latin. However, people eventually figured out that trying to apply Latin grammar rules to English is just silly.
For more information, please see: http://grammar.quickanddirtytips.com/ending-prepositions.aspx