x60 is useless, terrible screen and CPU is quite bad too by now

T60 only complaint is CPU

T510 this is the best laptop ever made, for simple web browsing if you dismantle a W510 and take its screen and put it in T510

T510 original screen is super bad

W510 is bad today because it has 2GHz quad core CPU and Nvidia graphics.single thread works very slow

T510 is incredible because it has the best dualcore CPU (it boosts to 3Ghz) which was available in 2010 and it has intel graphics and yet it has tolerable cooling as well. The laptop is still useless though if you cant find w510 screen.

T520 is bad, sansy bridge wasntr ready for this..
T420 is same but smaller

T430 is where things turn good again, the only bad thing is screen but 1600x900 version is at least tolerable

T440/T540 is the end of Lenovo, thing are in horrible state