Um, I just found that FreeBSD also exist as i386 image. Since I have some old 32 bit hardware laying around, I should test that out. Any things I should know before I put it to the test?
As you have noticed, it is one of the few systems that still supports 32 bit. After you have installed the system you will have to configure a few things. Eg the X server and a windows manager or desktop environment, the graphics drivers, maybe a few other things. This may be a little more difficult than with other systems.
But you also have to realize, after you have installed and configured it, it is one of the most maintenance-friendly systems. So it's just the initial setup that can probably take you two or three hours if you're not used to working with Linux or command line.
One last point to note, you are using an Atom CPU. They were already extremely weak when they came out. So I wouldn't install a desktop environment like KDE/Gnome/XFCE. The maximum that will be productive is LXDE/LXQt. If you have the skills I would even recommend using something like PeKWM, Openbox, i3, Xmonad, AwesomeWM, herbstluftwm, dwm,
spectrwm, .. Openbox and PeKWM are easy to configure and all the latter window managers are even more lightweight than eg an LXDE or LXQt. So you're going to notice that on an Atom CPU.