Is formatting a hard drive the same as re installing windows? In other words, do I have to do both? ( Im dealing with Win XP on an old PC)?

No it isn’t the same, formatting is preparing a hard drive for use by an operating system by erasing the data (or marking it as deleted) and setting up a suitable file system (NTFS, FAT32 etc).

That said when you reinstall Windows there is usually an option to format the hard drive during the install process anyway.

Why would you install an operating system that is both ancient and no longer supported?

That means you cant get online and be safe from hackers

no. formatting a hard drive will erase everything on the hard drive including the operating system. The you will have to Reinstall the operating system.

two different actions.

No, formatting is clearing the hard drive so you see an empty drive. XP will need the drive formatting before or during the installation.

no and yes. the formatting merely places a blank file catalog on the disk partition in the filing system format of your chosen FORMAT eg Fat32/NTFS/Other. These days thats all the Format does. so that means the FILES but NOT the data contained in them) just disappears from the catalog so the disk appears BLANK. Installing the OS adds files for the OS into the catalog and copies those files to that partition on the disk. The OS installations ALSO offers you the option to Format the disk. A full format(takes hours) probably also does not erase the data on the disk as that would take too long, it just checks every disk sector is readable(which is why it still takes a long time, but a full write would take much longer).

No.

Formatting is laying new tracks on the disk so that data can be written on it in an organized fashion. The process deletes everything stored in the hard drive.

Installing a program is the process of setting up a software program to run in a computer. Installation eventually must follow formatting to make the computer usable.

Make sure the old PC is within a few years before and after XP came out or else you will have trouble with getting drivers to run the hardware.