Having a difficult-to-guess or "strong" password is always a good idea.  If you manage an Active Directory implimentation (and your corporate politics will allow it), it's a good idea to require users to have strong passwords on your domain.

I recently learned of a nifty Microsoft online Password Checker tool that makes it easy to test the strength of your passwords: h<a href="http://www.microsoft.com/protect/yourself/password/checker.mspx">ttp://www.microsoft.com/protect/yourself/password/checker.mspx</a>

That information and TONS of other good info on the subject are contained in an awesome Windows Secrets Newsletter article by <span style="font-size: x-small;">Becky Waring, found here:</span>  <a href="http://www.windowssecrets.com/2009/08/06/01-Gmail-flaw-shows-value-of-strong-passwords">http://www.windowssecrets.com/2009/08/06/01-Gmail-flaw-shows-value-of-strong-passwords</a>

Windows Secrets is a paid newsletter.  I've been a suscriber for years, and have always found it to be a source of useful and interesting information.  The link above is to their public content.