"A lot of the excess CO2 and other pollution we generate is from our transportation sector. If we switched our power generation from natural gas and coal to more nuclear, solar, and wind, this transportation sector will still be a big problem."

"A lot" & "excess"?. The entire transportation sector is minor source of CO2:
http://www.eia.doe.gov/emeu/aer/eh/total.html
"Most energy produced today in the United States, as in the rest of the industrialized world, comes from fossil fuels--coal, natural gas, crude oil, and natural gas plant liquids (Figure 2). Although U.S. energy production takes many forms, fossil fuels together far exceed all other sources of energy. In 2000 they accounted for 80 percent of total energy production and were valued at an estimated $148 billion (nominal dollars)."

As you can see from graph, unless cars are still running on coal- it's small portion of fossil fuel.

And as this graph shows:

If add commerce and residential electrical use together you get more energy than transportation sector [ships, rail, plane, truck, and car]. Plus industrial use of energy is higher than transportation sector.

If you want to turn all cars into using electricity and want to reduce total CO2, than you probably need to at least double the number nuclear plants we have.
If all you want to do is reduce CO2, the best idea is build more nuclear plants in areas in which it is less economical to ship in fossil fuels, particularly coal, next heavy fuel, and lastly natural gas.