[CentOS] Xen tools

I have been playing around with Citrix XenServer Express. It seems 
pretty cool, and mostly meets my needs, except that the Express (Free) 
version only supports up to 4GB of RAM.  I have 8GB on my machines.

Since XenServer is based on Xen, I should be able to just install a base 
install of CentOS and use a third party management client to get all 
(most?) of the functionality of the XenServer without having to be 
limited to 4GB of RAM. 

Can someone recommend tools that I can use to manage the Xen hosts?  I 
see there is Ganeti, but that seems to be linux only.  I would prefer a 
windows or a web client, as I intend to have the actual Xen hosts be as 
stripped down installation as possible. 

As far as being able to utilize 8GB in CentOS do I need to install the 
x86_64 version, or is there some sort of AWE support?  I remember 
reading that x86_64 version has some compatibility issues. 

Thanks in advance,

Russ