Need computer help!

I am hoping one of the computer experts out there can help me. I need to buy a laptop for classes I am taking at night. I don't need anything really powerful, just something that can handle word processing, excel and powerpoint and websurfing. I will also need to download movies from you tube for class presentations. I am trying to spend no more than $500. I went to Best Buy to look but there are so many to choose from and I don't know where to start. Can anyone recommend me a good laptop based on the criteria I mentioned above and also where to get one? Is Best Buy ok to buy from or should I try on line? Thanks!!!