When I opened the a810n case I found the heat sink from the Asus K8S-La MB for the Sis 760 support chip lying in the bottom of the case.
http://h10025.www1.hp.com/ewfrf/wc/document?lc=en&dlc=en&cc=us&docname=c00257657
I acquired some 2part heat sink glue and re-attached it(hope I got the layer thin enough as it setup like any other epoxy). ~12 hrs later I reconnected the machine and it ran O.K but within 24hrs it was back to it's old ways. I was able to copy "My documents" and do a MozBackup to the 16GB flash drive I bought and succeeded in getting it all onto her new Vaio laptop with Tbird 3.1 (which incidentally I was unable to install successfully on my own AIIx2 Vista machine)
I'm going to try a recover process but I'm guessing the Sis 760 may have been fatally damaged so If I intend to resurrect the a810n, I'll have to get a new motherboard, rare as they seem to be.