Rebuild initrd to get dev-mapper working

[Hadders]

Hi all,
  I'm very close to getting my new hardware setup working. It kinda does.

I'm using the Intel SATA RAID to get RAID 0,  Grub as a boot manager, 
have installed XP and copied my existing FC5 setup "over" to the new 
container.

I can boot into this new setup, but only with the stock Kernel. When I 
try the latest Kernel, the device mapper doesn't work and as such, the 
system can't find the filesystems.
Over on the ata.raid list, someone has suggested that I run the following:

 > dmraid -a n && dmraid -a y
Which deactivates/activates the RAID container in one go?
Then rebuild the initrd for the latest kernel I have (but not running)

I would assume the safest place to run this command would be from 
runlevel 1?

Any tips would be appreciated.
Thanks. Hadders