Older versions, requirements

[mc_L20]

I am trying to revive an old Dell laptop that was running Windows XP and is really too slow for anything newer (it currently has Windows 7, which is how I know that  :-\ ). I started looking at Linux and actually tried several different distros on USB stick but most wouldn't connect to my internet, and the few that could were too slow. I just found a video about this distro and the system requirements were okay for my machine, but the video is 5 years old and Linux Lite is several versions past that. The current one has a requirement of 1gHz; my laptop is ~800mHz so I think the latest version won't work on it. I see that there are older versions available for download but I don't know their requirements. Are those available somewhere? I'd like to download the latest version that will run on this laptop.

The laptop is a Dell Latitude D631 that looks to have a Legacy BIOS (it's from 2008), with 4g RAM and a 120g HDD that is currently partitioned; I was going to put Linux in the empty partition but I couldn't get it any bigger than 16g, and anyway, I want to see what it does on USB first (assuming I can get a connection, which is another issue). This machine would be used only for Facebook, email (webmail), browsing, and audio/video stuff (YouTube, maybe some podcasts). The intended user (my brother, who is retired) doesn't have the skills to do anything else. If someone wants to recommend a particular version that's fine; I don't mind researching it, I just don't know where to look.

Thanks everyone.