There are a number of ways to do it.
Your question states about Windows Server disk. This is an different operating system and will remove your Windows XP.
There are many differences between Windows client and Windows Server, however, unless the site you are going to make will be "big", I would not recommend you go down this route as there are costs involved.
However, if you are going to be programming ASP/Asp.Net you will need to either upgrade to XP Pro, or get a server edition. The Windows XP built in Web Server is restricted, but does work well.
However, if you want PHP or simply static HTML, you can stay with Windows XP and take a look at WAMP, it is a single installer that will have you up and running in no time!
Simply put your content in a folder and it will be accessible to anyone via http://your.ip.address
I don't understand what you mean by web hotel.
If this is publicly accessible to the internet, you need to forward port 80 from your router to your machine. If it is a single internal network and you do not want outside access... if you do not set a firewall up, it should work on your internal address.
If you want a friendly name, you have two choices - if you have an internal DNS server, set up an additional entry with the name that points to your ip. However, it is probably easier if you already own a domain name, just to set one up with the ip of your external address (if you forward port 80) or just your internal address - if you only want people from inside the network to access. (This will simply time out for other people).
Hope this helps, and I know you will have follow up questions, this is not very straight forward, but feel free to ask and I will try to help you!