Use a Windows OS, you'll get more customers that way.
You can definitely develop windows applications on other operating systems. So it doesn't really matter.
Besides, the OP is 13. He's not looking to form a company. You'd need much more than $1500 to start that up. So amount of customers is irrelevant anyway.
I am new to programming and I need advice on what computer would be good and I am 13 so i have a budget of $1500. Also I would like advice on what language to learn first and how to go about learning it.
you got that from a job eh? always nice seeing a kid save money
nevertheless, you are not going to be programming anything that requires a mass amount of power anytime soon, so you really dont need a powerful computer for that. my 300 dollar laptop sucks but thats what ive been doing ill my programming on and its been working fine
however, think about your hobbies, if you like playing games, get a powerful desk or laptop thats windows ( as most games are made for windows because it is the largest market share )
if you're and artist of anytype you will also probably need a pretty powerful pc as well.
at your age it can never hurt to invest into a great pc because you really have no expense
you can buy a pc, why laptop?
you can programming in any programming language that you like:
in my idea, python is easy, so first learn it.
then C++ because you are not limited to somethink that you want to programming with it
for example, you can write any games in C++ and any requirements that it may have like 64 bit only
or you can write your applications for 64 bit computers in a 32 bit computer
then assembly because you have control the all of the hardwares
for example, you can destroy the memory or CPU or anythink that is on the case
and i recommend it because you can write your own Operating System