replacing 18g hard drives with 72g drives in a windows 2000 server

I have a windows 2000 server with a raid setup. i am replacing the 5 18 gig drives with 5 72 gig drives. i have a unitrends disk backup server that will reinstall the server in no time but how do i increase the volume sizes. i have heard that i can use partition magic once the server has been reinstalled and i have also heard that you cannot use partition magic on a windows 2000 server.