It is the difference between night and day. Saving a government versus taking one over without a mandate from the people. Below, for instance, is a CPAC video (H/T Christian Conservative) that shows the absolute truth about a possible 2004 agreement between then Official Opposition Leader Stephen Harper, NDP Leader Jack Layton and Bloc Leader Gilles Duceppe. They clearly state they were NOT proposing a coalition government but a “working arrangement.”
That was VERY different from the 2008 Liberal/NDP/Bloc coalition, which was intended, not only to ursurp the winning Conservatives, but to allow the NDP into Cabinet. No, in fact, the 2004 situation was the exact opposite of the 2008 situation. For further details on the reason for the letter, see this previous post on the topic.
For the full CPAC video, click here — the truth from their own mouths!