The main problem upgrading motherboards is AHCI Sata drivers, if it don't boot pass the little color balls you will need to reset the SATA Driver, if it does keep booting it will just install all the new hardware it finds then restart else just use any missing drivers off the MB CD.
If it don't boot just download Hiren's Boot CD boot
Choose > Mini XP
go to the Menu in taskbar > Registry > Fix Hard Diisk Controller
Press T for Target and set it to C:\Windows > Enter (you can check the drive letter for main os by clicking "My Computer" icon)
Press M to update Mass Storage Controller

Restart Remove CD

If Hiren's don't boot go into your BIOS and set the SATA Mode to IDE instead of AHCI ** but once you restart after fixing HDC in Mini XP go back into your BIOS and set it back to AHCI.

If Hiren's don't fix it there is another fix that will do it, you just need to boot from you Win7 DVD, so let me know how you go.