OSDev.org

Hello,

I want to write my own OS sometime... But what do I need to know? What's a kernel and what's a bootloader? Is there a very beginners-tutorial out there? And when I look at projects from other fellows, I can't get them to work...

forget the big projects and start with a simple one.
take a look at this article.
http://osdev.neopages.net/tutorials/pdf/basickernel.pdf

for bootloader,
www.geocities.com/mvea/bootstrap.htm