I think that New technologies and rends are invented now a days so it is possible to have this type of functionality.
If Core i7 has 4 cores then the laptops of Alienware M17x is what you are looking for. They say its the most powerful laptop in the universe!
I have an i3 processor and I'm pretty impressed with nehalem architecture. It's actually a virtual quad core. Really amazing for laptop performances. I greatly recommend it
i3 acting as a quad core processor i7 comes with quad code but its costly so i should prefer i3 or i5
the Op said as Dual core + Dual Core as Quad Core Number of Cores I3 - 2 Cores (But acts as a 4 Core Processor) I5 - Similar to I3 but Advanced than that 17 - 4 Cores