I know the hack you speak of, as I have run it, but decided against it because of speed.
All the other raid types that non-hacked XP uses work in Vista, and I suspect you may jst eed to import the volume.
I do have an issue in that dual booting between vista and hacked xp, I constantly have to import the volume if it was previously used on the other OS, and this pplies going either way.
if vista last used the array, I hav to import into XP, and vice versa. I am actually going to be putting 3 more drives into that box in about a week, so maybe I'll set them initialy for raid5 and see if I can bring them into vista.