How do you distribute server disk space?

I have a Compaq ML370 running a Raid5 array. My OS is NT 4 Server SP6. I just added a new 18.2 gb drive. I’ve configured it as a second logical drive. How can I take its unused disk space and add it to my existing C and D drives, increasing their free space? Is this possible? Any help would be greatly appreciated. Thanks. 🙂