What MVP does in hybrid crossfire/SLI the IGP with the dedicated GPU to get you about 10% improvement. If you have no IGP then you get nothing. LOL
The difference between hd2500 and hd4000 will be minimal when using hyperformance mode so grab whichever processor is faster. A real 4 core, such as the i5, would be recommended if you plan on playing BF3 multiplayer, otherwise the i3 will be fine in just about every other game.