I can't answer your question regarding a magic sound replacer for Oblivion, but uploading any of Oblivion files, even if it's something with minimal effect on the game, is not legal. So you'd have to take a sound replacer for Oblivion.
The mod I use in Morrowind for replacing my magical sounds is http://planetelderscrolls.gamespy.com/View.php?view=Mods.Detail&id=1990 from Lucypher.