Update has killed PC with a C0000218 stop

When I shut down my PC last night I got the message that there were 3 updates
to be installed. I selected install and shutdown then went to bed. This
morning my PC will not boot and I get the following:

Stop: C0000218 (registry file failure)
The registry cannot load the hive (file):
\systemroot\system32\config\SOFTWARE
or its log or alternate
it is corrupt, absent, or not writable

I've removed all power and tried booting...no go.
I've tried the recovery console and run chkdsk...no luck.
I've run the recovery console and verified that the files in ..\config\ were
modified last night. Some have and extension of .old. Can I restore these
files and get back running? Is there some way to roll back the updates?

HELP!