My old PC (Pentium IV @ 3.4 GHz, 1 Gb RAM, ATI Radeon 9550 256 Mb) was running Windows XP until Microsoft's support ended. I had to either risk keeping the XP or changing the OS. Since Microsoft OSes are paid and tend to be resource-hungry, I switched completely to Linux in this PC. Between Mint, Debian, Lubuntu or Crunchbang, I went for Lubuntu (as you probably guessed by the title).
Lubuntu 14.04 is actually a pretty nifty and soft-running OS in this PC. It does not consume much RAM, the CPU is not frequently pushed hard, and so far, (almost) everything goes well.
Since it's an old PC, I have some tips which may be useful when using it. These tips are also arguable, and the post is not closed (I'll possibly add more stuff while using this PC).
Keeping tabs on everything:
htop allows you to check how much of your CPU and RAM you are using, as well as how much of those resources each process is using up. To install it:
sudo apt-get install htop
It looks something like this:
You can use it to evaluate which processes consume more resources, and choose which programs are better for you. I used it, for instance, to check how Mozilla Firefox (installed by default) and Midori compared.
A less RAM-hungry browser:
To install it, according to the browser website:
sudo apt-add-repository ppa:midori/ppa && sudo apt-get update -qq && sudo apt-get install midori
Or download the deb file, and use gdebi (read this post).
From My experience, Midori is much lighter on RAM, but randomly'ish pushes hard on the CPU. If your problem is lack of RAM, go for it. I recommend it for simple searches when you have other software running on your PC. But Midori is nowhere near as stable and complete as Firefox. That's why I use Firefox for more often.
I'll add more stuff soon!
Overall, Lubuntu is a very good, stable enough, and pretty OS which can give anew life to your PC.
