You can use quite a number of "underlying" distributions, it mainly depends on what you like (Arch-based ones, Debian-based ones, etc).
As a desktop environment, have a look at XFCE or LXDE.
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Linux is a family of open source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991 by Linus Torvalds. Linux is typically packaged in a Linux distribution (or distro for short).
Distributions include the Linux kernel and supporting system software and libraries, many of which are provided by the GNU Project. Many Linux distributions use the word "Linux" in their name, but the Free Software Foundation uses the name GNU/Linux to emphasize the importance of GNU software, causing some controversy.
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You can use quite a number of "underlying" distributions, it mainly depends on what you like (Arch-based ones, Debian-based ones, etc).
As a desktop environment, have a look at XFCE or LXDE.
something that runs xfce
Manjaro XFCE ftw
I have successfully run Arch with Openbox as WM on machines even older than that. Arch has a learning curve, though.
And therefore it should not be recommended to Linux beginners... It is not a beginner distro.
There is no such thing as a "beginner distro". There are distros that need little to no intelligence to set up and maintain. Arch needs you to read and follow instructions. It is a myth that it is impossible for beginners to use Arch. There are several good installations instructions in the wiki, select one and follow it till the end.
There are also plenty of Arch derivates that preconfigure the system for you.
I beg to differ and say, even when the Arch wiki is a great source of knowledge, setting up own Arch system and maintaining it requires keeping on track with updates, to understand what is wrong with your system to look up the right keywords and so on. In my opinion it is better to stay on a stable, periodically released distro with tested repos like Debian, Mint or Ubuntu at first. Afterwards, you can still switch to Arch.
by GUI, you mean with GUI installer right ? if yes then i recommend Debian