Should I buy an Apple or Window's run laptop?

I'm planning on investing on a new laptop, but I'm not too sure what one to get. I have a lot of questions on the topic and would love you to help me out with them!
I'm a school student, so I can't afford a really expensive laptop but I need to upgrade mine, I have had it a while now and it's beginning to go down hill.
My choices are: Apple mac book, or an Asus laptop.
My parents have very kindly offered to buy me the laptop itself, but that leaves me with buying the software and things for myself.
Questions about getting an Apple product:
Do I have to buy Keynote, Pages, Photoshop, Numbers and all those separately?
Would my normal hard drive connect to it? ( it's an external hard drive but not apple)
Questions about windows:
Do I have to buy, Word, PowerPoint, Photoshop separately?

I have an iPad that I was given from my school, and I also have an iPhone, we use Apple Mac's in school so I'm familiar with Apple software, but I use Window's at home so I'm familiar with that too.
I use my laptop a lot with school work but I'm using the old windows… So I'm lacking a lot of updates that are available.
Although my parents said they would pay for my laptop, I don't want them spending loads of money and then having to keep paying out for things, so I want that laptop to last a fair amount of time.
I know Apple products are being increasingly popular, and I would like an Apple Mac Book but they are quite expensive, and to be honest if windows can offer me the same for less then that's a whole lot better! I love the Apple products, but I enjoy using windows.
Hope someone can answer my questions and break it down for me.

I sell laptops everyday.

Yes, you do have to buy the programs in addition to the computer with Mac or Windows. You can format your external hd to work with Mac. Instructions can be found on YouTube. Many consumers don't like Windows 8 because of how different it is. Go to your local Best Buy for a test drive.

It also depends on what area you are studying. For graphic design or photography, the industry standard is Mac, even though the PC can run all Adobe programs. If you want to game in your spare time, stick to the PC.

However with a Mac, you can have the best of both worlds and actually have Windows as well. This is a dual boot.

Some say Macs can't get viruses, this is false, though the chances are less likely. Hackers want to target Windows because they are the majority. I recommend a good anti virus like Webroot or Kasperski.

So here comes my personal experience… I have had my MacBook for years and use it to its maximum potential in graphic design and photography, and it's still going like the day I bought it.

Either way you go, you're getting a good product… Just don't skimp out on insurance for your computer… Because any of them can fail instantaneously and you don't want your investment to be unprotected.