Sorry, clearly I misunderstood your question.
Logged on as Admin in W2K pro Sp3:
First, I installed Nero 5/InCD,(Nero5 retail CD), updated both. I used Custom StartUp v2.0 to keep the tray Icon from starting w/ Windows 2000. Rebooted.
Then I used an EZCD 5 Plat. retail CD to install DCD. I chose custom install and chose only 1 item, DCD. Nothing else was installed. Rebooted, then I installed the latest EZCD v5.3 update, rebooted.
Checked the option in DCD to show tray Icon. Used Custom StartUp 2.0 and unchecked DCD and it's Project selector utility from starting w/ W2K.
When I need to use one or the other, I just click on the desktop icon or from Start-Program Files. I use Task Manager to close/Exit them.
I can use DCD logged on as any user. With InCD, I have to be Admin or use the (buggy for me) Nero Burning Rights utility, to use it as other than Admin. DCD lets me format CDr's and CDRw's just fine, so I may just dump InCD for now. hth.