external storage for linux

[David Vincent]

hi list.

i'm looking at my options as i try to trim the number of computers i run 
in the house yet retain some fault tolerance for my data.

i'm interested in recommendations from anyone on what to use as 
500gb/1tb external storage with some fault tolerance.  this would be to 
replace a pc running three drives in a raid-5 which is hooked up to ups 
and shuts down nicely when the power goes out.  raid-1 would be a 
minimum for me.  power handling is a nice extra.

which leads me to ask if i put two 500gb drives in two different 
external enclosures and hook those up to two usb ports on a machine, can 
i raid-1 them?  mounting them to the same spot is easy with uuids etc so 
without trying it i think it should work.  maybe someone out there 
already knows and could offer some advice.

how about external NAS systems?

thanks!

-d