It's not difficult to set up, but it is a little tedious. I got the dual boot working from the RAID Volume on the first try (yeah!). Followed the guide here. Note that Celena has the grub folder in lib/grub and not /usr/lib/grub like in the guide & Cassandra (for the section where you copy the grub stages).
Basically to do this you boot the live CD and install the "dmraid" package. You should pre-partition your RAID with something like Partition Magic because gparted doesn't get along with dmraid too well (otherwise you can use the terminal). After dmraid is loaded and the RAID volumes are activated your RAID partitions are mapped to /dev/mapper and you can run the installer. When you get to the partitioning stage there is a little extra work because the RAID partitions show up twice each and you have to tell the installer to not use the un-numbered partitions. After that the install runs as always until the end when it tries to install grub, which fails. You then use the terminal to mount your RAID file system and chroot into it to manually configure grub.
Of course the first thing I did after getting it working was screw up my xorg.conf file.
And for some reason my anti-virus in XP decided to stop working? Got those sorted out without too much trouble and both systems are running normally now. Haven't had much time to play with Celena yet, but she makes a good first impression. Not running at the correct resolution at the moment though, so I'm gonna go screw up my xorg.conf file again. 
Aloha, Tim
And yes, I am fully aware of the risks involved with running a RAID-0 array. There is a non-RAID data drive on the system for backups and important files.
