How do I install Linux operating system (Fedora/Ubuntu) in a PC while I am using Windows XP and how to exist both of them after linux installention? How do I select which one will be the default operating system? Describe full step as you know. Thank you.

First of all you will need to partition the system, if the hard drive is entirely taken up, then you need to use software such as Partition Magic to chop it up.

Then you have to go through the installation of Fedora/Ubuntu, when asked specify that there is another operating system on the computer, ie: Windows.

Post installation, you will notice that when you reboot, you will get prompted for selection of the operating system you want to boot.

If you are not, and you are scared that you lost everything, make sure that you have your windows XP cd handy, put it in, then press F6 for recovery mode, and type FIXMBR. This will resotre the Master Boot Record so you are able to boot into windows, then try again because you have have missed something.

Actually you don't need top do any of the above. I recently instally the current Ubuntu release (7.04) and the partitioning is done during the installation. The entire installation routine is shown here: https://help.ubuntu.com/community/GraphicalInstall

It assumes you want a dual boot system if it sees another OS.

Ubuntu installation has a very good installation wizard and you just have to read all the instructions carefully so that you don't delete your existing OS and your files.

Installation guide:[Ubuntu 7.04]

1. Insert Ubuntu disk
2. Run the live OS
3. Click on the Icon to install ubuntu
4. Follow the instructions
5. Reboot and choose OS to run