I was wondering if the Western Digital USB hard drives (passports) are any good for long term back ups? http://www.costco.com/Browse/Product.aspx?Prodid=11119342&whse=&topnav=&browse=&s=1 Are they stable? Any increased risk of data loss over CDR or a firewire external hard drive? Any risk of thermal melt if they are left plugged in? (they lack a fan or vents) Anything else to be aware of with them? I like the passport USB system because there's no power cord or wallwart to mess with And their capacity is increasing (used to be 75gig, now up to 125) so they are more useful.