I did some more research on the settings part of Windows Vista gadgets and storing username/passwords in plain text in your settings is not a smart thing to do.

You can use the JavaScript code below to do basic encryption and decryption.

        function encrypt( plainString )
	{
            if ( plainString == "" ) return "";

            var xor_key = 2;
            var result = "";
            for( i = 0; i < plainString.length; ++i)
            {
		result += String.fromCharCode( xor_key ^ plainString.charCodeAt(i) );
            }
            return result;
	}

	function decrypt( encryptedString ) 
	{
            if ( encryptedString == "" ) return "";
            var xor_key = 2;
            var result;

            for( i = 0; i <  encryptedString.length; i++)
            {
		result += String.fromCharCode( xor_key ^ encryptedString.charCodeAt(i));
            }
	    return result;
	}

Read more background info here.