Which chipsets exactly? what will not be supported? Unless there is some major problem that will prevent the old kernel from running or you need some specific support then the kernel should boot and just use generic drivers etc. You should at least be able to get to a prompt and recompile your kernel from there.
nforce2.
Actually, I just didn't think the kernel would be so forgiving, and apparently I only need updated kernel drivers for the net cards(!) and audio. I had anticipated there to be a kernel panic, generic mobo drivers will apparently be ok.
Also, the current nvidia graphics driver supports 8x AGP (Version: 1.0-4191, 11 dec). I guess the proof will be in the pudding if all the kit arrives tomorrow! *bounces around* ;)