Problem with New MSI P7N Platinum

[Cleared]

Hello,
First, my english is not very good but i give it my best shot

This is my computer :

Msi P7N Platinum ( first had P5K SE)
2x EN9600GT (first had 1)
E8500 @3.16Ghz (standaard)
550w Antec earthwatt voeding
4gb ddr2 ram
320gb hdd
v8 cpu cooler
1 cdplayerr en 1 for burning
__________________

This is my problem:
I have bought a New Mobo MSI P7N Platinum, and i want to install in my computer last week. After hours of work :P (to get everything out and the new mobo in) i tried to start it up. It will start up, but it stucks in the bootscreen. I tried several things, like: checking all connectors, unplug the unnescessary cabels, just 1 ram bench, other sata port for harddisk, etc.
nothing worked.

So i brought it to a shop called Epsilon. they tried to make it and did this: Other harddisk with windows xp and it started up and stayed on for 1 min and then shutted down or falled out or something. They putted in an other CPU (an older cpu).

I really have no idea what it is. I read on some sites that is the bios. it has to be updateted. But i am not realy clever ( dont know the word, somehting like dont have the brains for :P) with computers. My friends are helping me now, but at the moment they do not know it either.

I hope somebody can help me , cause i spend like 125 euro on this mobo xD

Thank you, and bye!