According to Video Business, the first version of the Lord of the Rings: The Return of the King DVD will be released in May, with the extended version expected in September. Also in the works are boxed sets of both the regular versions (May) and the extended versions (Q4).
Assuming the boxed set will contain all three films, I'd probably get them (both theatrical and extended). Although my current collection is going to be one act short.
No I don't accually. I have both versions of both FotR and TTT on DVD, just because each DVD has different extras. I just know some companies take out stuff when they change the packaging of DVD's.