I think he may actually be talking about the mobile editions of the i5/i7, since he mentioned getting an Nvidia 650m. If this is the case, then know that all mobile i5s are dual-cores, and not quite as stalwart as their desktop counterparts (I'm currently working with an i5-2410m).
But that doesn't mean they're bad processors. My 2410m combined with Intel HD3000 runs most games at low settings @ 1366x768. My friend's 2410m combined with a GT550m runs most games at high/ultra settings (no AA) at 1366x768.
The i5 is fine for laptop gaming - don't sacrifice the GPU to get an i7. The i5 will likely show its age a bit sooner than the i7, but the i7 won't have much more time over it.