Merging two partitions in 2000 Server

I need to find out if there is a way to merge two partitions on a HD within Wind 2000 server? I have two SCSI HD set up as a RAID level 1. When I was setting up the RAID, I created a partition of only 4 gigs on a much larger drive. Later I when Irealized my error (after bring the server on line) I set up the rest of the space as a D partition. Can I merge these two together within Wind 2000, or do I need to buy some third party software like Partition Magic to do this?

Thanks
Ray