If the 10.4 system is running 10.4.11, Norton AntiVirus 11 for Mac would run on both systems, as it supports 10.4.11 to 10.6.
As for the Boot Camp partition, you'd need a Windows version of Norton AntiVirus to protect that operating system. Norton AntiVirus 2012 is the most recent version for Windows, and still supports Windows XP, as long as it's service pack 2 or above.
Symantec used to sell a dual protection product -- it came with the Mac version and the Windows version -- to protect Macs running both operating systems. That's no longer available in the store since NAV 2012 was released.
I don't believe Symantec directly sells NAV 11 for Mac either, as the only Mac AntiVirus version in their store is now NAV 12 for Mac.
(NAV 12 for Mac does also include NAV 11 for Mac on the disk, for customers who aren't running OS X Lion yet, but it doesn't include a product activation key for the older software in the box. If you purchase NAV 12 for Mac, you'd have to contact Customer Support for assistance in activating the bundled NAV 11 for Mac product. Alternately, you could look for other merchants who still have NAV 11 for Mac in stock.)
Those are the details about the products that would protect both your Macs. The one answer I don't remember is about the upgrade path from NAV 10.1.2. If you have an existing subscription, perhaps someone else knows if that entitles you to migrate to NAV 11 for free or not, within your current subscription term.
Hope that information helps!
