Vectorworks is a powerful drafting program that is comprised of several industry packs.
The industry pack most useful for theatre is Vectorworks Spotlight. Spotlight has built-in libraries for most lighting fixture manufacturers that include wattage, beam spread, weight and color frame size.
Student website (a full-featured "Educational Version" is free to qualifying students, see site for details)
A great site to learn from
Of course, we must discuss Software History also. With the introduction of the Macintosh in 1984 came MacPaint then MacDraw. Then came MacDraft, followed by ClarisCad. About 1993, Blueprint (Diehl GraphSoft, Inc.) begat MiniCAD (1996?), which begat Vectorworks, when founder Richard Diehl sold to the Nemetschek group.
1983, John McKernon's ALD begat ALDpro, which eventually became LightWright4 which is a Specialized spreadsheet-like Lighting paperwork program that works interactively with Vectorworks Spotlight.