Uruguay v. Ghana
It's actually been a fascinating sociological demonstration how South African fans (and African fans more generally) have gotten behind the sole remaining African team. I doubt seriously other continents would have this level of unity. While Ghana has won consistently in the past years through a stifling defense. However at the end of the day I think Ghana will miss Michael Essien's play making abilities as Uruguay match's the Ghanan defense but has more striking capabilities.
Brazil v. Netherlands
This might be the best match of the quarter-finals. The Dutch have looked as good as anybody. They have a ton of experience, firepower, and their best player is finally healthy. However Brazil is top dog in the soccer world more so now as they've adopted a more defensive focus. Too many stars, too much firepower as soccer royalty moves on to the semis.
Paraguay v. Spain
I think I speak for all mankind as I'm rooting for Paraguay given that super-model/super-fan Larissa will strip naked and run around if Paraguay wins. Umm go Paraguay? Unfortunately Spain is the #1 team in the world by rankings led by David Villa and Xabi. They tossed aside Portugal, who is better than Paraguay, so Spain should role in probably the most lopsided of the quarterfinal matches.
Argentina v. Germany
Germany I think has shocked a number of football/soccer fans. The youth/foreign movement of the German squad has been more successful then I think initially projected. Their crushing of England demonstrates the importance of infrastructure for a national team (as England lacks one). However there's something about this Argentina that seems more than the sum of their substantial parts. Despite barely making the World Cup, Maradonna's squad has looked as impressive as anyone in South Africa. In the end, I'll pull an ecological fallacy and say because South America has been better than Europe...Argentina gets the win