my lenovo t60 had blue screens since a few months ago. it became more frequently lately.. i knew it was overheating as i could tell by touching the bottom; it's very hot. until today i couldn't live with it any longer so i opened it up, cleaned the dirts and lints on the fan blades. now it runs with a warm bottom, not hot. i am pretty sure it's cured.
you will need a small philip screw driver (depending on your brand) and maybe other tools too. for mine that's only i needed. a small tube of heatsink thermal paste will be used when you install the fan assembly (radio shack has it for $12.99, but it's like a ripoff to me. i went to a pc repair shop and got one for $1.99). i didn't need to disassemble the fan assembly, just used wet swabs to wipe out the dirts and lints on the blades and mouth blew inward to clean the grills. if you can't mouth blow, you would need to get a can of compressed air.
it's not hard but need patience. good luck.