Recommendation for a RAID hardware enclosure?

[evilned]

I have an original SHeevaPlug, which has worked wonderfully for several years, running off of a USB 2.0 hard drive.  Recently however, I've been worried about hosting so much of my data with a single point of failure, so I've been interested in getting a USB 2.0 raid enclosure.  Anyone have a good suggestion, or would I be better getting an actual NAS at that point?

[skrap]

I've had good success with a DNS-320 NAS.  It's cheap, and not pro-level, but it's gotten the job done for me.  That said, I've not had to try to recover from a failure yet!