This demo features a sample of the full version’s single-player content, including:
» An interactive tutorial for new players
» Two different missions from early on in the GDI single-player campaign
» One 1 vs. 1 skirmish map, pitting you as GDI against a computer-controlled Brotherhood of Nod army
» The entire GDI arsenal at your command, from the Mammoth Tank to the Ion Cannon
» The entire Brotherhood of Nod arsenal for you to fend off, including the Obelisk of Light and the Tiberium Vapor Bomb

Command & Conquer 3: Tiberium Wars Demo (Right Click -> Save As)

The link above is from EA, I got a constant 1.5 MBps (megabytes per second if you are wondering) and I completed the download within 15 minutes. The file size weights 1.17GB in size.