Re: ? about multiplier
When you raise the multipler you raise only the CPU speeds. If you raise the FSB you raise the CPU, the FSB, the memory, the PCIe / PCI slots etc. A lot of different components get their speed from the FSB. That being said, a lot of the higher end boards also allow you to change the divider to other components and which ones are linked to the FSB.
It can be a little confusing at first trying to figure out how everything relates to each other, but the reason there are so many different possibilities is that it makes it a lot easier to get the speeds you want. Having a CPU with an unlocked multiplier I would say go for the multiplier as well.
The one thing you will notice with the multipler is that it is done in large steps, so you may get to a point where you can no longer raise the multiplier because the gap is too large. This is where rasing the FSB a little can help get you some extra speed without losing stability. A lot of it is trial and error but what a lot of people do is figure out what the max speed they can run the CPU at by rasing the multiplier and writing that down. Then they take and lower the multipler below stock speeds (In your case 8x would be good) and then they increase the FSB until it becomes unstable. this way they can get an idea of how far they can push the FSB without the CPU causing problems. After you have those numbers then you can play around with the multiplier and the FSB and find a happy medium which gives the best speed.