Hello and welcome to the forums.
I tend to do the conversion and choose to not power the VM on afterwards. When the conversion completes, I make hardware changes as required, and then make sure that "Connect at Power On" is not checked under the device status for the network adapter(s). Now you can power up the virtual machine and do whatever you need to do to it to get it ready (uninstall old management software, change HALs, etc) without fear of it being on the network with the same name and/or IP address. Once everything looks good in Device Manager, Event Viewer, etc - I shut down the physical server and then power up the VM with a "connected" network adapter for testing.
Another option would be to use the "Customize the identity of the virtual machine" option towards the end of the Import Wizard, if you need to be able to have both the physical server and the virtual machine on the network at the same time. This customization will allow you to give the VM a new server name and SID, and then you could just assign a different IP address to it.
Good Luck!