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.
Also, during that time the President of the United States declared that any country from their allies if demanded help to end communism, the US would provide it. However, when the Vietnam War broke out, the Cold War was going on still between the US and the Soviet Union, and the tensions were at its peak. So, the US actually had its plate full of problems to deal with. One was the Civil Rights War within the country, the other was the Vietnam War and another was the Cold War. In retrospect, the United States did not do much to end communism and it ended on its own. People in the world are not stupid and they do not need a superpower to put an end to their problems.