Here are my picks ...
India will win against Bangladesh (With a name like Cowboy&Indian, you expect me to pick Bangladesh? Go India).
New Zealand will beat West Indies. New Zealand is on a roll and WI just made it into the quarters by the skin of their teeth.
South Africa are famous as chokers, so I think Sri Lanka will win. Also, de Villiers seems to be the only South African playing ...
I don't know whom to pick for Australia vs Pakistan. It is home turf for Australia, but Pakistan seems to be on a roll lately. Also, this Australian team is nowhere as good as the guys from the Ponting/Gilchirst era. But as an Indian, I have to pick Australia.
I agree on India v Bangladesh, Bangladesh have done well (including a rather close match v NZ), but India should win that.
The Blackcaps should beat the West Indies, although who knows if Chris Gayle fires up, he's already scored a double century this WC.
I'm not sure about the SA vs Sri Lanka match. Probably Sri Lanka, but they're carrying a few injuries, so maybe South Africa will actually win a WC final :)
Unsurprisingly, as an Aussie, I think Australia have a pretty good chance at that match. Pakistan have only scored above 300 once in this World Cup (against UAE), and losing Irfan will hurt them with the ball, especially at Adelaide. Australia have better batting depth (especially when you consider Haddin is at 8 and Johnson (at 9) can bat) and Starc has been bowling brilliantly. Although if Pakistan gets a few early wickets, Australia could struggle to post a score. I'm not sure how some of the mid order bats (ie: Maxwell) would go if it's 40/3 after 10. If Pakistan win though, an India v Pakistan semi final would be HUGE.