When you write or respond to a HTML-formatted message in Outlook 2003, and paste some text from another source (e.g. a Web page), the pasted text looks out of place because Outlook uses the string's original formatting, which is almost always different from the formatting in the message. If, like me, you find multiple fonts in a message ugly, you'd want to paste the text into the message without any formatting, as in MS Word's Paste Special command. However, when editing a message in Outlook 2003 in HTML format, the Edit / Paste Special menu item is disabled. According to this thread, it's only enabled if you use MS Word as your editor!
One workaround is to use GnuWin32 commands and a pipe: getclip | putclip. getclip outputs the unformatted string from the clipboard and putclip copies its input string back into the clipboard. Now, when you paste your text, it won't have any formatting.