Installing any of the following Linux on your older hardware will be very easy. The good thing is that there are many tutorials or guides provided by the team itself to help new users. Also you will need to do a little research about the applications you want to install on very tiny distributions. Prefer the application that uses less system resources and has a simple user interface. If you maintain the installations then there will be no problem using any of the Linux listed above.
There’s a dedicated server section of the Arch Linux Wiki. You can learn all about configuring Arch Linux as a server operating system. While there’s not a pre-packaged server release available for download, this Wiki provides the steps to creating your own. You can install popular server software including MySQL, Apache, Samba, and PHP for Arch.