Back in 2010, I installed Ubunto 9.04 on an old Win XP laptop infected with numerous viruses, turning it into a great internet machine for things like Facebook, Youtube, and forums like this. It was also my first laptop, so it was special to me, especially since I made it into something useful for schoolwork and personal uses. I did end up giving it to a friend later on when I got my first "official" laptop preloaded with Win 7. Now, I've been thinking again about Linux and I've been curious about jumping back into messing with all the distros. Some of the knowledge I had when using it four years ago has kind of faded, and I kind of need a refresher here to get started again. Also, what new distros and versions would suit me for my purposes? As a side note, instead of turning an old computer into a Linux machine, I'm thinking of running it on one of my numerous flash drives that I have laying about on my computer desk. They range from 512 MB to 16 GB, so space won't be an issue. Thanks for the help. =)
I would recommend some flavor of Ubuntu. It is more user-friendly than many other distros, but not to the point of being insulting (i.e. hiding everything - you can still dig in and tweak away). It is always kept up to date, updating packages and the OS is a breeze, and driver issues are mostly a thing of the past. I'm not a fan of Unity (the newer Gnome GUI), so I would personally recommend Kubuntu, with KDE.
I would suggest just getting VMWare (free virtual machine software), and then playing with various distros. Once you figure it out, VMWare is kinda cool. Takes only a little bit to set up, and you can then install any flavors of Linux-Unix you want. On my main PC I have Mint, Ubuntu, SCO Unix (the successor of Microsoft Xenix), and at one time had Corel Linux (a Debian based), Sun, and several other versions. I even have images for VMware that run Dos 6, Windows 3.1 and Windows 95. And on my work computer (Mac) I use Virtual Box to run Ubuntu. This lets you play with one or several before deciding on one that you like best. https://my.vmware.com/web/vmware/free#desktop_end_user_computing/vmware_player/6_0
It runs in Windows, and lets you "install" various operating systems and run them inside of a virtual machine in Windows. Anything beyond that is largely irrelevant to 99% of users.