After more than a week of testing combinations, i've managed to install Debian etch (amd64 version) on my new Core 2 Duo system. It required using the latest daily build and putting my IDE CD-ROM into my USB IDE enclosure - it appears that the the problem is that Debian kernels haven't got a pata_marvell module yet. Interestingly, OpenSUSE 10.2 installs perfectly. More details can be found at Debian bug report #397062.
Now on to my next adventure: installing Xen. :-)

Update
Incidentally, i never got Xen working to my satisfaction, nor X.org's X server. I ended up buying a dirt-cheap add-in PCIe card, and i'm running VMware for my Windows emulation. The graphics card i bought was an ATI Radeon X300SE, which i bought from msy.com.au (for AU$38!). It shows up like this in lspci -v: