It'll work on the tv, but not project the max number of pixels a hdtv based system would... that's all. Bottom line, it will work on a hdtv but not to the tv's full resolution.
The Wii is confirmed not to be HDTV compatible, but as long as the right connectors are present, you can still hook it up to an HDTV, it just won't look as good as the HD signal.