It's going to be just fine. Don't worry :)
Don't forget to check out Prague's architecture as much as possible. And just mix around with the natives all the time. You're going to feel pretty stupid at first, 'cos you won't understand a thing in rapid speech. But after around a week of deep immersion, sounds sort of start trickling in.

Don't let the occassional xenophobe get you down. People are pretty friendly there towards foreigners in general, but there're always exceptions, just ignore those.