Right decision imo.
RAID is a complete waste of time outside of certain specialised (high-volume) server uses.
RAID 0 doubles the chances of data loss on the logical drive (two drives = twice the chance of failure) for an entire 10% (on average) speed increase. Woah dude, that's totally worth it.
Span is similar.
RAID 1 halves the chances of data loss on the logical drive with the slight downside that it's horrendously expensive in terms of £/MB as it doubles that cost.
RAID 5 and derrivatives are more sensible solutions, but require expensive hardware support cards if you don't want to be relying on the processor to do it, and need at least 3 drives to work.
In other words, forget it