Can I use the merge feature to create a virtual machine? I am planning to add a few more old boxes and would like to know before I try it.

Thanks

Not a good idea. WHenever the client communicates with the server, a last message ID is sent, and if the server and client do not agree, a new host is created on the server. In this case it should split the hosts apart again.

Just allow BOINC to create a host for each real machine that you have. I have a collection of 9 machines some of which are quite slow.
<a href="http://www.boinc.dk/index.php?page=user_statistics&amp;project=cpdn&amp;userid=13"><img border="0" height="80" src="http://13.cpdn.sig.boinc.dk?188"></a>

Thanks. That is what I was wondering about.