In Jaguar, choose a document and control-click it to bring up the contextual menu. Now press the option key and the "Open With" item changes into "Always Open With." This makes it easy to change the document type without opening the Info dialog.
The same thing works in the Finder's File menu. Select a document, then File, and then press the option key to see the revised menu selections, one of which is "Always Open With."
Mac OS X Hints
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