Don't kill the Opus tasks. There is never any need to kill them under normal circumstances, and doing so can corrupt your configuration. (Not a problem if you're about to replace it, but it's still a bad habit and unnecessary.)
Instead, fully exiting Opus (via File / Exit Directory Opus).
That will stop dopus.exe cleanly. (It doesn't matter if dopusrt.exe stays running so don't worry about that one.)
Then, copy the configuration folders (using Explorer) from the old drive to the new drive, and re-launch Opus.
Details on where to find the configuration folders are in this FAQ, under Locating the config files by hand:
The Before copying config files by hand section in the same FAQ also expands on the reasons for exiting Opus first and how to do it.