Simple external RAID backup?

[Scott Ehrlich]

I'm looking for a cheap external raid solution for a RedHat Workstation 5 
box.

My plan would be a device, such as possibly the 
http://www.cooldrives.com/qubayalretru.html

and load it with four drives.   Since the device itself likely does not support 
RAID 5, I'd anticipate the four drives could simply appear as four individual 
volumes, and I'd use the RH 5 tools to create a software RAID 5.

Any known problems/limitations with this idea?

What other, similar devices, possibly more reliable, are available?

Portability would be really nice.   If the PC it is connected to goes down, I 
could simply build up another box and connect this device to the new system.

The goal is to have it act as hard drive storage for backups of mounted CIFS 
volumes.   Not currently mission-critical data, but it would be very nice to 
have a low-cost RAID 5 backup setup to start with.

Thanks.

Scott