My NAS is broken (all Leds green). This page explains how to recover a NAS200-disk on a liunx.
Take one disk out and connect it to a linux-box. Boot linux and run the following commands:
mdadm -A --run /dev/md0 /dev/sdb1 mkdir /mnt/sdb1 mount -r /dev/md0 /mnt/sdb1
Now, the files may be accessed (read only) under /mnt/sdb1