Are there huge drawbacks to using an excel 2010 document for password management?

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http://serverfault.com – At my old job, we used an open-source, (IMO) secure method for managing network infrastructure, and other important hosts' passwords [with Keepass]. At my new job however, it seems like they're using password-protected excel spreadsheets. Before I made a fuzz about password security, I browsed the interwebs and found that Microsoft has been getting better at implementing encryption features to their office products. Main questions: How safe is MS Excel/office 2010's password encryption feature? I've been thinking this was an insecure way of dealing with passwords, is this not the case a (HowTos)