Lubuntu 20 Dual booting

I have a Samsung Note book PC (Samsung NP-NC110) which is running on intel Atom processor, 2 GB RAM.320 GB HDD that is pre-installed with Windows 7 starter now Microsoft stopped security updates to Windows 7. i don’t want to loose OEM partition of windows 7 starter but i want to dual boot this Notebook PC.

The configurations of my PC is very basic so i tried Lubuntu by creating a persistence Bootable USB Live with Rufus software. When i am running Windows 7 its consuming 600 MB of RAM in idle condition as well as Lubuntu consuming 350 MB of RAM and i installed some applications what i needed. Compared to Windows 7 Lubuntu handling those software programs very well. If i put some load on both operating systems Windows 7 getting slow due to out of RAM but in Lubuntu its taking space from swap partition and it handling the tasks very well without any lagging. so my question is why Lubuntu 20 not supporting to Dual boot and what is the best OS after Lubuntu for Dual boot that is compatible with Atom Processor. Please share your ideas. I am already using Ubuntu Focal in my another PC.