You should use both attributes. The language attribute is deprecated. The type attribute is the new one. Old browsers don't support the type attribute. A strict html 4.0, or xhtml 1.x page won't validate with the language attribute, but no browser really can do strict html since support for cascading style sheets is so bad.
(edited by: Xoc at 4:17 pm (gmt) on July 14, 2001)