The exact size, of course, depends on the playing time (in minutes and seconds), on how good the original compresses and the compression quality. 1 Mb a minute is a good approximation, in practice. I wouldn't trust 2 Gb to hold 1000 average downloaded songs. Just go for 4.
The causes of the Vietnam War were derived from the symptoms, components and consequences of the Cold War. The causes of the Vietnam War revolve around the simple belief held by America that communism was threatening to expand all over south-east Asia.
Fifthly, the Nuclear Programme of America was responsible for another cause for the Cold War. After the bombardment of America on Hiroshima and Nagasaki Soviet Russia got afraid for her existence. So, it also followed the same path to combat America. This led to the growth of Cold War.