Multiboot system with asterisknow, FC 7 and XP

Hello everyone;

i have a question please. I wish to configure my laptop machine with an external usb hard drive, with FC 7 and Asterisknow. My MBR is on the lap top’s native hard drive. The grub is sitting there. Therefore at present i have FC7 and XP dual boot. The FC7 sits on the external hard drive. While XP sits on the laptops native drive.

Asterisknow as you might probably know, is an ip pbx with its own OS. I think its CentOS. Now i tried to use the free space on my external hard drive which had a FC7 distro on it, to install Asterisknow. I created an additional primary partition on the free space (around 47gigs) and formatted it to hold /opt file system. I did get an error, saying that i must have a /root partition on that drive (sdb), i thought the already existing root partition would suffice but i think i was wrong, why did that happen? please share an insight. Whats the work around that, cant i have more than one Linuxes on th same drive on two different partitions?

Would asterisk now need its own /root, /boot and /swap partitions?

How can i configure grub to boot xp, fc7 or asterisk? i did try however, the grub failed o load asterisknow or fc7, i had a kernel panic message when i chose to boot into asterisknow and when i tried to boot into fc7 i had a message saying OS not found and chainloader+ failed (or something to the same effect).

any help would greatly appreciated.

best regards.