Please read it carefully and read the link about the mystery of the missing partitions. I am seeing this happen more often as people move more and more to Vista. They copy stuff to some USB or other connected drive and plug it into their other Vista machine and then the room temp feels like it plunged 50 degrees as they can't find their precious (files.)
A lot of this issue is mitigated if you put these on a NAS and never connect directly with USB, Firewire or SATA.
At least you've been warned about the issue and will keep your backups current.