I think what matters most in your case is the desktop environment, not the distro. I would suggest something lightweight and fast such as Xfce with the distribution of your choice. Gnome and KDE tend to use (a lot) more resources than Xfce. I personally use Debian stable with Xfce on all my machines (which includes a Thinkpad x220), but the Xfce default settings are not ideal on Debian so you will need to fiddle with them (it can all be done easily with the GUI, but it isn’t the most user friendly experience at first). If you want something that looks good outside the box that resembles Windows I would suggest Linux Mint Xfce Edition, very straightforward and easy to use with good looking defaults !
I think what matters most in your case is the desktop environment, not the distro. I would suggest something lightweight and fast such as Xfce with the distribution of your choice. Gnome and KDE tend to use (a lot) more resources than Xfce. I personally use Debian stable with Xfce on all my machines (which includes a Thinkpad x220), but the Xfce default settings are not ideal on Debian so you will need to fiddle with them (it can all be done easily with the GUI, but it isn’t the most user friendly experience at first). If you want something that looks good outside the box that resembles Windows I would suggest Linux Mint Xfce Edition, very straightforward and easy to use with good looking defaults !