[Zope] How to best use Zope on SMP machines?

Hi :) I am to use Zope on a SMP machine which has 2 Xeon HT cpus (so 4 logical processors). As far as I know Python is not multithreaded, so the full potential of the server will not be used... How can I change that? I was thinking about running a couple of identical instances connected with ZEO and then using some load balancing between them. Do you think this is a good idea? How many instances should I use on a machine I have described, four? Are there any cons of such a configuration? I am open to any suggestions on how to use the machine's power best :-) Best regards, Maciej