Keeping NAVCE from fouling up NA's Virusscan NT

Help guys! I'm assisting someone to put NAVCE onto their server but part of their workstations have a preload of Network Associates Viruscan NT on them that they don't want to uninstall. They did it once and fouled up the workstations. Anybody have any ideas?
Reg

I am a bit confused about a "preloaded" McAfee VirusScan NT. What is the engine's version number?

You might want to apply the <a href="http://www.mcafeeb2b.com/beta/products/vscsp1-intro.asp" target="_blank">Service Pack 1</a> or use the <a href="http://www.mcafeeb2b.com/beta/products/4160-intro.asp" target="_blank">4160 engine (RC1)</a> to correct any problems and then uninstall it completely.

If they are using a management console (Management Edition, Total Virus Defense, ePolicy Orchestrator), make sure the agent is also removed from the workstation before you proceed with NAVCE.