Laptop suggestions for Computer Science major

I’m going to be majoring in computer science and I need recommendation for laptops. I have never owned a laptop before or used it too often, I always have used my desktop when I’m at home. Below is a list of what I think should be enough for my laptop.

  1. I'm trying to keep the budget below $500, but if it is absolutely necessary I'll go above that.
  2. I don't know what size screen I really need for my major, but I'm thinking 14'' or 15'' (you guys tell me which is better). I also need the laptop to be lightweight.
  3. Battery life should be decent as I'm going to be taking it with me to classes obviously.
  4. I prefer Windows 8 OS, but Windows 7 will also do.
  5. I do prefer this laptop last at least 4 years for college.
  6. I'm thinking 500gb hard drive is enough (if needed I can buy a external hard drive). I dont need a SSD because they usually tend to cost more.
  7. I'm thinking 4gb RAM should be enough.
  8. I'm not sure what type/kind of processor I need but hopefully i3 is enough?? <-- (I don't even know if that made sense to you guys)

Check out the lenovo y40. Get the base model used (should be around 400) and it has all the processing and graphics power you will ever need.

I would suggest a newer processor and something with a super long battery life (this is essential and more important than anything else for a college laptop). Screen size doesnt matter honestly. Try http://bit.ly/1Hde37P or something similar

Toshiba C55-B5101