How much of a performance increase (if any) will I see if I build this desktop?

[OneFIshSunfish]

Currently I am using a decent laptop:
cpu: i7 3635QM 2.4ghz
GPU: radeon hd 8870m
RAM: 8gbddr3
laptop model is a series 7 chronos NP77oz7e-S01UB
the build I have planned is
MOBO: MSI Z97 Motherboard Model#: Z97S SLI PLUS
CPU: Intel Core i5- 4670k
GPU: evga geforce gtx 660
RAM 8gb ddr3


This would be the first time I've built a tower so I'm not to sure I've done it correctly. could anyone also tell me what psu I'd need for the build.

 

[okcnaline]

It'll actually be worse. Get more money for a better GPU.

 

[Tinkmaster Overspark]

in terms of game performance, the real thing that matters more than anything is the GPU. Almost everything else is secondary for gaming. spend big on the GPU