I had a Buffalo Linkstation 250 Gb for about 18 months - after this time it failed with all my data on
Buffalo support were useless and said I had to lose all of my data (most which was additionally backed up fortunately)
They never sent a RMA to return it - in the end I gave up took the linkstation apart and removed the data - which was a job in itself as it has it's own file system which windows doesn't recognise, you have to have a working knowledge of Linux/Unix - in the end I did remove the data only after incurring additional cost
I have other Buffalo things which are very good but my experience of this put me off having another NAS I just back up with portable hard drives or monthly back ups to DVD - not so convenient but so far more reliable