I can confirm that CDS works fine on a 'Dual-Boot System'...
I have 'XP Pro' and 'Vista Home' installed on my 'Pi2515 Laptop'.
CDS is installed on both O/S's.
In 'Vista Home', I have set CDS to Protect the 'XP Pro' Partition.
In 'XP Pro', I have set CDS to Protect the 'Vista Home' Partition.
... Any worries I previously had about conflicts between the Two O/S's, or Programs writing to the wrong Files/Partition, are now in the far reaches of the back of my mind...
So basically, CDS is protecting both O/S's from each other.

Thanks again Comodo for yet another awesome Free product!

(R)

But here's a question: Why do you need to have two OS's on the same machine?