Open IE. goto tools>internet options>programs
here check the last checkbox and restart IE. then answer yes to make IE default Browser.
you are done. congrats.
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Holding my last breath, safe inside myself.....
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I dont use my computer. I misuse it- रोलरकोस्टर
You might also want to go to Opera Preferences->Advanced Tab and in Programs of left menu, there is option for asking Opera to check if it is default browser. If you continue to use Opera also, you might want to set it up to false to prevent it from nagging you at its startup...