Booking through Rail Europe in English is very convenient. I input Krakow and Prague on this page with good results: http://www.raileurope.com/us/rail/fares_schedules/index.htm

You can email your questions via the Rail Europe web site: http://www.raileurope.com/us/common/have_question.htm

I suggest you do a price comparison for flying vs. train travel, try http://www.Expedia.com or http://www.Orbitz.com

Hope that helps, Linda in Toronto