I have a question, My aunt & uncle have an old Compaq Deskpro 3/25i which is running WIndows 3.1. My cousin are intereested in learning how to use LINUX OS. We were wondering is it possible to replace the windows 3.1 OS with Linux OS. And if so, what steps should we take in order to change the OS? Thanks in advance.

Just format the drive to remove the DOS/Windows install, Linux recognises FAT16. A basic Linux Distro, which can also be installed alongside windows try http://www.slackware.com/zipslack

Dont expect much from Linux on that system. Graphics are possible, but this machine is much better of with Windows 3.1x as it is now. Experimenting on this old machine will also be very time consuming. But if you still decide to do it you will learn a lot I guess. Anyhow you will need a very old and/or tiny Linux distribution (like TinyLinux). If you want to experiment with newer and bigger Linux versions and all of its (graphical) possibities I suggest you use a new computer. I once tried to make a dual boot system from a 133Mhz/32Mb/1.2Gb computer using Windows 98 and a newer Linux distribution only to find out that my harddiskspace and other specifications were not good enough to run it smoothly (I used Corel Linux, which is even old by now). In other words: For experiments with Windows 3.1x your computer is good enough, for graphical Linux its too slow....