Buy a NEW Triple Monitor Setup w/ Intel Core i3-3217U or Buy a USED Intel Core i7?

Hey, for the past month, i've been hanging onto my money deciding how to spend it, and I have concluded with two decisions.

I will either buy a TRIPLE MONITER SETUP with a laptop with I3-3217U + Intel HD 4000.

Or I will buy a USED i7 laptop, i7-2670QM, 4GB DDR3, 600GB SATA HD, NVIDIA GeForce 610M with 2GB DDR3 VRAM.

My intel i3 is fairly new, and runs fast on the games I play ( Minecraft, TF2, Black Ops 2 ) but sometimes I think i need to expand it with multiple monitors and/or buy a new laptop with i7 but used.

If i buy the monitors, i will buy 2 more monitors, the cables and a gaming keyboard plus a gaming mouse.

If I buy the new laptop, i will receive faster fps on games, and i will be able to give my old i3 one to my little sister.

WHICH IS THE BETTER CHOICE, I CAN FRICKIN DECIDE!

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