Eucalyptus or OpenNebula or... for a Linux and Windows build server private cloud

We are setting up an 8-machine build farm. Most of these builds need to happen on a specific flavor of Linux (Fedora 10 as of now), while some of them will happen on several different Windows VMs. We were considering using Eucalyptus or the Ubuntu Enterprise Cloud to run the Linux VMs, and just have VMWare on a couple of machines dedicated to Windows builds when we need them. However, it seems that OpenNebula would work in a similar fashion, but allow us to have some or all of our nodes running VMware's free (as in beer) ESXi.

So my questions are:

1. What do you folks see at the big differences between Eucalyptus and OpenNebula?
2. Are there strong reasons to prefer one hypervisor over another? How about VM format? (is KVM easier to use with Fedora, for instance?) Windows support makes ESXi the most likely choice, but I'm wondering if there are any gotchas.
3. Does any one system's administration and monitoring make it preferable to the others? We'd likely control them mostly through script interfaces used by our build tool.

Thanks!

Solution 1:

As far as question #1, this came up in the OpenNebula mailing list some time ago:

http://lists.opennebula.org/pipermail/users-opennebula.org/2009-July/000551.html

As for question #3, IMHO, I'd say OpenNebula has a much more modular and extensible design (making it, among other things, more script-friendly).