Windows 2000 Server Setup Problem

I am in the process of setting up a Windows 2000 Server with an 80 Gig IDE harddrive. I want to create a 10 Gig NTFS C: drive. During the installation process I can manually delete the partiton and re-create it. When I try to create the 10 gig partiton I am unable to change the size of the partition. The size is currently 76309 and I cant change it.

What am I doing wrong.