When you increase the screen resolution, things are smaller. Fundamentally the only way to get things bigger again at higher resolutions is to have a bigger screen. Magnifier, zooms and increasing font sizes just allow you to tweak around the edges of what kit you have to make the best compromise.
I use 1920x1080 and I have my text size set to 125% (and IE9 zoom=200%), but I have a 24" monitor which is much bigger than a laptop screen.