The Season Seven DVD set for Region 1 fans (the United States, Canada, etc) is due to be released tomorrow, December 7th. You can currently pre-order the set by clicking here.
Additionally, the Season Five, Region 4 set (Australia, etc.) is due to be released a day later, on December 8th. The Season Five, Region 2 (United Kingdom, etc) is due to be released in January 2005.