Switch running System to RAID-1

Hi,
I just figured that our complany's server was running on JBOD with 2 HDs, one of them entirely unused (d'oh!). Of course I would like to have it as RAID 1.

Now, I built an Array from the HD in use and know how to make it bootable, but I suppose I have to make some changes to the boot-config before it will run as before. Which could these be?

Also (probably a common question) how can I make a backup boot CD-ROM with the current settings? Is there a good HowTo around?

Alex

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system info:
hwinfo says the Controller is "Intel 6300ESB SATA RAID Controller".
boot-loader should be GRUB.
Kernel 2.6.8-2-386.

PS: Needless to say, I have a complete backup.
PPS: Posted this the second time here because I was told it was OT in Linux Boot list, where I posted initally.