Losing hi-res with Xen kernel

[Chris Jones <cjns1989@gmail.com>]

I did the following to set up a Xen dom0:

1. squeeze AMD64 install on a new partition
2. apt-get install the Xen packages (cf. Xen/debian wiki)
3. tweak the grub2 environment and install it to the MBR
4. boot the Xen dom0 kernel

Now, the odd thing is that while doing steps [2-3] above, I'm working at
my preferred 1920x1200 resolution, but after I boot the Xen kernel, I'm
down to 1280x800.. 

When I reboot into that system pointing to squeeze's original ‘non-Xen’
64-bit kernel, I'm back at 1920x1200.. 

Has anyone witnessed a similar scenario..? 

Could it be caused by some peculiarity of the Xen-ified kernel that
prevents the ‘nouveau’ driver from loading and results in a fallback to
one that does not support my display's optimal resolution..?

Any idea how I should go about fixing this..?

Thanks,

cj