On many Windows 7 installations there is a 100MB partition and the main system partition. For most situations, the 100MB partition is not necessary but can make backup more difficult. The case where you do need it is if you want to encrypt the entire hard drive using bitlocker.

If you want your Windows 7 installation not to have the 100MB partition then the solution is to setup the partitions using another program such as the Windows XP setup disk or various Linux disk partition managers.