Just cleaning up this report. The patch to fix this bug was included in the Ubuntu Feisty kernel. I'll include the git commit id and description. Marking this 'Fix Released'. Thanks.
Author: Phillip Lougher <email address hidden>
Date: Tue May 1 17:06:51 2007 +0100
UBUNTU: Fix pata_sis crashes preventing booting
OriginalAuthor: Alan Cox <email address hidden>
Signed-off-by: Phillip lougher <email address hidden>