Exactly.
The Marvel chip is crap, and will provide you with LOWER performance than your Intel SATA-2 controller.
You see, what happen is that Marvel worked on SATA-3 controller, but someone had the brilliant idea of making it for PCI-E 1x. The result, is that you are blocked at SATA-2 speed by the lack of PCI-E lanes. Genius, I know. He should get an award.So we have all been had. And for teh simple fact that its seperate chip, its performance is reduced. Hence why the Intel SATA controller, will be faster.
But it's ok. Your SSD even if its SATA-3, will not be limited by the SATA-2 controller in everyday use, because small file performance is really far from reaching anywhere close to SATA-2 speed. So unless you work with GB files, like doing video editing and such, you will not be affected. Including games.
So Windows will fly, same for your programs, including PhotoShop, and other large programs, and games will have a noticeably faster startup time (varies between game to game, as it depends if the loading process is due of loading multiple files, or your CPU/GPU is at work in loading the stage/level/match/syncing other players).