According to Feed Flix, the following shows will be streaming via Netflix starting on April 1.

24 Seasons 1-7
Angel Seasons 1-5
Arrested Development Seasons 1-3
Better Off Ted Season 1
Black Adder Series 1-4
Bones Seasons 1-4
Buffy, The Vampire Slayer Seasons 1-7
Dollhouse Season 1
Firefly The Complete Series
King of the Hill Seasons 1-12
Lie To Me Season 1
Life on Mars (US) The Complete Series
My Name Is Earl Seasons 1-4
Prison Break Seasons 1-4
The Riches Seasons 1-2
Roswell Seasons 1-3
X-Files Seasons 1-9

And as if that weren’t enough, these movies all premiere between April 2-15:

Bubba Ho-Tep
Donnie Darko
Earth Girls Are Easy
The Fly (1986)
Godzilla Raids Again
Gojira
Moon
Revenge of the Nerds
A Scanner Darkly
Star Trek IV: The Voyage Home
The Testament of Dr. Mabuse