As for refurbished models, stay away from T410 with discrete (NVIDIA) graphics. I own one and experience nothing but troubles with the thermal design.

I am doing everything to keep the GPU from frying my fingers on the keyboard and/or causing emergency shutdowns

- got the heatsink replaced by customer service

- cleaning the fan regularly

- tune software fan control, nevermind the noise

- check and replace thermal grease

- switch away from graphics-heavy desktop environment (Unity...)

- switching off webgl support in my browser

- ...

Well now that I put it like this, I am thinking it might not be worth the whole effort :)