Windows NT server

We had a NT server that stored some data on it that crashed over the weekend. I’m trying to re-install the OS but am running into some problems. I deleted the C: partition where the OS was stored than it gave the Drive Letter of C: to another partition. This is where my problem starts. I can’t install the OS on that newly called C because it’s too big, and the unpartitioned space I install the OS onto is getting a drive letter of I: than installing the OS on I:\WINNT. Is there a way to swap the drive letter of I for C? Any advice would be greatly appreciated.
-Kevin