Building a webhost

Hello.
I am looking into building a hosting system as a learning thing. I'm pretty unsure when it comes to this area. I have a few questions:

What operating system should i use? I currently have Windows XP
What are the min system requirements for a very small hosting server. Currently I have 2GB Ram on a slow processor
What Management Utility should I use (Free is better as I only want to build for the fun of it, not to use)
How do i go about registering domain names?
Whats a good billing and user management system?
What software should i use (apache?)

Are you looking to do this to host your own websites or for other people to pay you to host their website?

Neither. Its a learning thing. But imagion as i was going to sell it

It is hard to answer your question. You have to decide if you are looking to host your own website or host clients website.

I understand what you mean to know...
You want to be in hosting business selling different hosting plans...

I will suggest you to host your site fist market it properly have some reseller plan so that you can sell your plans without any prior knowledge of hosting, you don;t have to be master in technical stuff if you find any problem you can contact any time to your host;
Your host should support 24*7 for all issues. ( I suppose you are interested for doing hosting business )

Yes, hosting business is very profitable if managed properly....

Note : I can help you to setting up your hosting business; Please mail me with your budget so that i can explain you better....

For fun and learning, i would suggest either switch windows 2003 or linux OS. Domains can be registered from any registrar. If you are planning to serve from cable internet, make sure port 80 and 25 are not bloked by your ISP.

You will need to set up you firewall policy and block all unnecessary ports to prevent your server being attacked as soon as it goes live.

If you search google for setting up your server, you will find good tutorials.

Happy learning and have fun (: