Resizing NT boot partition

I have a delema I need to solve.I am quickly running out of harddrive space on my servers.I have 9G Scsi drives with mirror.I have 2 partitions along with system the partition.I need to resize my system partition were the Nt files are stored.Or preferrably add bigger drives and ghost over my system files.This is my primery domain controller I need to do this with.Any suggestions?Help!!