While it's not clear from your message what those characters represent, you can certainly replace formatting without losing the text. In Word 2003, open the replace dialogue with Edit/Replace (Ctrl+H or Alt+E,E), place your cursor in the "Find what" box, and click on the More button, lower left. At bottom left, you'll see a Format button, which will reveal a menu including Font. When you have selected the font and characteristics you want to replace, move your cursor to the "Replace with" box and choose the font and characteristics you wish to have appear. Then click on Replace all (Alt+A).

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