Hardware repacement informatin

I am getting ready to replace a SCSI hardware raid array with a new
3ware Escalade ATA hardware raid array.  I am in the planning stages of
performing this change out and have a couple of questions that I hope
some can answer for me.  First I plan to add the ATA hardware raid card
and setup the IDE raid array while the SCSI raid array is still
connected to the system.  This is where I am not just exactly sure how
to proceed.  So my question is - Can I just copy everything over on to
the new array (directories, partitions, etc.), remove the old SCSI array
and move on or do I have to first do an install of RH 7.2, partition
etc. on to the IDE array first and then move the data to the new drives
before removing the SCSI array?

And no there is not enough room in this system to house all the drives
for both arrays permanently.

Any assistance will be greatly appreciated.

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