Vista - Please 'elp. Will Acronis True image back up my dual boot sytem (2HD's)??

Hi folks, i'm a noob, so if i ask a silly question, don't flame me

Okay, so my PC has two HD's; one with Vista64, one with XP32.
I have to hit F8 on boot up to be able to select a HD to boot from, otherwise it defaults to my Vista HD. But both HD's can see each other and can be accesed from either operating system via 'My computer'.

I have one boxed copy of Acronis True Image 11.
So, my question is thus :

If i install Acronis In Vista (and to the Vista HD) and i want to do a full system back up to a bootable DVD (using Acronis), will it also back up my XP drive so that in the event of an emergency - both drives and operating systems would be returned to their original (bootable) states??

Or would i need to install Acronis twice; once on each HD and make 2 seperate system backup DVD's from withing each operating system??

Any help would be really appreciated, as i'm going in circles at the moment