[Zope] The best way to set up Multiple Zopes?

Zopista's, I want to set up multiple Zope's on my Linux Box (6.1 running Apache with Virtual Hosts). The sites need to respond to different URLs and I think they should have different ZODBs. So... the questions are... 1) What is the best way to do this? (Proxy Pass, Zope.cgi, etc) 2) Has anyone done this and what has been their experience? 3) Are there any resource issues in terms of memory, processor, etc? Thanks, J