If it is a SBS 2008, it means that you don't have more DCs and more exchange servers. So the restore process is in some way simple if you have the correct backup in place, you just need to make a complete recover of your server and it will be done
But the questions are... do you have a complete backup of your server and is it compatible with AD or/and Exchange? How old is the last available backup that you have? Were all the information and data in your hard drives totally lost?