Best options to format a WD My Book Pro II

[rubaiyat]

I have just purchased an external Western Digital My Book Pro II which consists of 2 x 750Gb drives and a RAID card. The ports are USB2, FW400 and FW800.

The software supplied by WD allows for formatting to RAID 0 and RAID 1 with no provision for Linear/Concatenated.

Disk Utility does let me format it to Linear/Concatenated.

I have just had a a HD fail on me so I am very cautious. It seems to me the risks associated with such a set-up are:

The power supply, which is external so replaceable.

The RAID card - never used one before so not sure how this works or its riskiness.

The 2 drives, the Master and Slave.

I think the RAID 0 Striped configuration is too risky.

The RAID 1 Mirrored configuration is better but only half the capacity and I wonder what actually happens if the RAID card fails or the Master or the Slave. Can I just remove individual drives and get at their contents in another case?

If I format to Linear/Concatenated, do I assume any risks to all the drives if the RAID card fails and /or I get a failure in the Master or Slave drive?

I'm totally new to this, so I'd really appreciate guidance from wiser counsel.

Thanks s:-)