Okay, let me explain again
* I am able to install LMCE in a HVM, but that has no access to any pci(e) hardware. At least not without VT-d which is only available on a small amount of MB's and using a Intel procc. So the only way I can hook the system to the network is via virtual network interfaces and that causes congestion. Not to mention not having access to ISDN cards and so on.
* Installing in an unpriviledged domain (PV) will give you access to PCI(e) through pciback.hide but when building the domain the installer of LMCE fails. When I did overcome the latter (tearing the installer down into bits and pieces) I was able to install the lot, but the system was everything but stable...
So if there is a way to install LMCE as a PV I would certainly give it a go and if able to build would provide the VM as a appliance to everybody interested.
I see where your going now. On an semi-unrelated note. XEN supports AMD-V so the range of Hardware supported VEs is larger then you think. Any newer AM2 socket board will support it, but yes that does limit the availability of the solution. Also as of 3.3 Xen has some support for PCI pass through for hardware visualized environments. I have been meaning to give it a try to see if they have reach the level of support for video cards but I have not found the time or the hardware.
However Xen does networking (in V3.0 or lower) it does it strangely. In the past I had tried with out success to use IPtables rules on the Xen Host to filter traffic to VEs. Rules that should have worked failed to allow appropriate traffic. Now that Hardware virtual environments have access to PCI pass through (v3.3) I was going to fiddle around with having a PFsense (FreeBSD) hardware virtualized environment route all my Xen traffic for me by giving it direct access to the NIC. However, I haven't put together the cash to get the hardware.
What version of XEN are you using? Is it just the through put or are there other Network issues? What's the through put when the Xen host pushes traffic? What type of hard drive is the Xen hosts using (IDE, SATA, SAS, SCSI)? What is the Available RAM in the system and how much are you dedicating to the LinuxMCE VE?