Redhat has you covered and it’s absolutely free.  While it’s somewhat limited you can download a live CD of the software running on the server.  The system is powered by Amazon Web Services.  The system should automatically scale to what ever you need.  Even if you need to expand there is no additional cost.  It’s interesting how little chatter we have heard about it.  The interesting part of this is as much the free download to compete with VMWare as it is that we and a lot of others have missed that this happening a year ago.