How close are we to WWIII?

It seems everyday there are more and more conflicts. The US alone is currently occupying multiple countries including Afghanistan, Iraq, and now it looks like we have our sites set on Libya. I'm not too well informed so am unsure how militarily active other countries are at the moment, though I would error on the side of more aggressive. Combined with many countries already at war with neighboring enemies and with themselves, it seems things are quickly reaching a tipping point. In your opinion is WWIII inevitable? If so, are we likely to see it within the next 20 years?