Was working thru this issue recently to get a VM to work with ESXi 6.5. We ended up having to find a copy of ESXi 5.1 and use the VMware vCenter Convertor 4.0.1 and convert the VM under VMware hardware version 4 and by increasing the C:\ drive or the drive that has boot sectors by roughly 20 GB’s in size.
After the VM was successfully converted, we performed a snapshot of the VM, then upgraded the VMware hardware version to 9, then from a Windows Server 2008 server we used the VMware vCenter Convertor 6.0.0 to convert the 2000 NT VM to ESXi 6.5 since we were unable to install anything about VMware vCenter Convertor 4.0.1 on the 2000NT box. We when upgrade the VMware hardware version to 13 and used ESXi 6.5 U1.
The plan is to phase out Windows Server 2000 NT at some point, but at-least now the 18 year old server can be stable in VMware for the foreseeable future. 🙂