Seagate's been pretty dang busy lately, duking it out with Western Digital for the title of top HDD manufacturer. So busy in fact, that the company nearly forgot to celebrate its 1.5 billionth drive sold! The milestone was reached on October 20, only 2.5 years after Seagate cracked the 1 billion mark in April 2008. Selling 500 million hard drives in 2.5 years is quite the accomplishment, considering the fact that it took 29 years to ship its first billion.

Seagate said that its first billion drives equated to 79 million terabytes, enough space to store 158 billion hours of digital video or 1.2 trillion hours of music. With an extra 500 million units under its belt, those figures have ballooned to approximately 118.5 million terabytes, enough for 237 billion hours of digital video or 1.8 trillion hours of music. At its current sales rate, the company expects to move its 2-billionth drive within the next 2 years.

To celebrate its achievement, the company is giving away one 1.5TB GoFlex ultra-portable external hard drive to three winners. To enter, post a comment on Seagate's blog post by 5PM PT, November 15. Alternatively, you can snail mail your name, address and contact information to: Seagate 1.5 Billion Shipped Blog Sweepstakes c/o Corp. Communications, 920 Disc Drive, Scotts Valley, CA 95066. Names will be drawn on November 19.