Which operating system? If you have a SATA hard disk and the old and the new motherboards are configured the same (IDE, AHCI or RAID), then it should work. However you will have to load new drivers for some components, e.g., Ethernet controller, CPU, sound chip if they're different, etc. At a minimum you want to make a complete backup of your hard disk just in case something goes wrong.
Currently I have Vista, however I have ordered W7. I suppose I could wait & buy the components now & then install everything together.
Thanks for replying to my question.