AMD Phenim II X2 555 in old mobo

Hi guys. I want to get a Phenom II X2 555 Black Edition and put it in a Gigabyte GA-M57SLI-S4 rev 1.0, 4 Gb DDR2 A-data 800MHz, 4850 radeon. I know the bus speed will downgrade, but will this work? (i cant buy a new mobo cause i dont have the money )
The only problem i can find is that i curently have bios version F15D and i need F15E to support the cpu and it wont let me install it on win7 64bit...aparently i need 32bit OS. Any ideas on that?

Thank you for any input.