I want to design an operating system to pc which is completely different from Linux,Dos,Unix,Mac os X and etc,?

If you want to design a complete operating system from scratch, you'll need a lot of energy. Just ask yourself why Microsoft erans so much money with their Windows OS, and why Linux OSes take so many people so long to program. It's not the kind of work for one person alone.

If you want to learn something about OS programming, you'd probably be best off taking one of the systems available (Windows, Linux etc.) and find out how to alter parts to suit what you want.

I'd suggest taking one part of such a system and formulating a question about changing it, googling that question and seeing what advice others have posted on the internet. For instance:

How to alter size button on window in linux?

You might also try that kind of question in YouTube. There are some very good video tutorials to be found there.

Many people ask this question and it's usually a gross misunderstanding of the level of complexity which comprises the hardware and software of a working general purpose computer system. However for change I would like to encourage rather than discourage, just for novelties sake.

First learn a programming language. doesn't matter which one but learn it fully, which should take a few months.

Then search on the piratebay: building a modern computer from first principles. This should also take you a few months or more depending, but it's not at all impossible if you have the time and the dedication. If I had the time I would jump at it but I don't. This will not only take you through the hardware side of how a computer works but also guide you through building a small operating system. It can also be constructed virtually using software provided from the site: nand2tetris.org

Good luck.

Umm yeah that you may, you probably have a Mac Duel Core processor. You dont want any hacking knowledge, and there's FREE application which you can download referred to as Bootcamp, which Statik recounted. If you're trying to run home windows an mac apps on the same pc, i might wait until the new Mac OS comes out (Leopard). It's going to be in a position to run home windows and mac applications on the identical OS with no need to partition your harddisk. And its no longer unlawful anymore. No one can tell you which processor that you would be able to or cant run an OS on.

In addition to the above, you're going to need an in depth knowledge of hardware and how to build drivers for it. You're also going to needs years and years of time to develop this if you are working alone. If you are not working alone you're going to need money to pay the people working with you.

You're going to need a computer science degree first... preferably a graduate level degree.

Then come back.