Quantitative easing weakens the dollar instead of strengthening the dollar since more money is put into the M3 money supply. Although the fed claims that its main purpose is to drive down interest rates, many believe that the main reason is to weaken the dollar so that US companies will have a competitive trade advantage.
The 6 months prior to the credit crisis, the US dollar approached $1.60 to the Euro and US exports were booming. The US main competitors are Europe and Japan and with a weak dollar against those currencies, airplane, heavy moving equipment, heavy machinery, and high tech (both hardware and software) exports should increase significantly. Also with the weak dollar, more plants by foreign companies (eg. autos) should be built in the US to remain competitive in US pricing.