Could I use a Lenovo 23" monitor for old gaming system like ps1 and Atari 2600?

The 2600 requires an RF connection channel 3 or 4 whereas the PlayStation will do RF, composite, S-video and I *think* RGB.

I don't know exactly what ports your Lenovo has but if it's VGA/DVI/HDMI/DisplayPort, you will require a signal converter.