Going by raw math, if the Earth were a perfect magic sphere with no atmosphere, you could attain "orbit" at ground-level by accelerating to 7.90 km/s. Then you could Hohmann to LEO with one 0.06 km/s burn to transfer up and another 0.06 km/s burn to achieve a circular orbit, so that's only 8.02 km/s in an ideal world. [Oh, I forgot that you start with about 0.40 km/s from rotation if you are near the equator.]
Oh, finally found a nice reference, on Wiki: http://en.wikipedia.org/wiki/Low_Earth_orbit#Human_useThe delta-v needed to achieve low earth orbit starts around 9.4km/s. Atmospheric and gravity drag associated with launch typically adds 1.5–2.0 km/s to the delta-v launch vehicle required to reach normal LEO orbital velocity of around 7.8 km/s (28,080 km/h). It doesn't break those out, unfortunately.
They aren't independent, though. "Gravity drag" comes from the fact that you need to put in 1G just to remain at constant speed. It's thus most efficient to have as high acceleration as possible. Unfortunately the aerodynamics work in the opposite direction: you don't want to go fast because that increases aero losses and there's a limit to how fast you can go in the lower atmosphere without breaking up. So the combined effects probably mean that the net loss is quite a bit larger than you could achieve if you only had to minimize one of them.
Going by raw math, if the Earth were a perfect magic sphere with no atmosphere, you could attain "orbit" at ground-level by accelerating to 7.90 km/s. Then you could Hohmann to LEO with one 0.06 km/s burn to transfer up and another 0.06 km/s burn to achieve a circular orbit, so that's only 8.02 km/s in an ideal world. [Oh, I forgot that you start with about 0.40 km/s from rotation if you are near the equator.]
Oh, finally found a nice reference, on Wiki: http://en.wikipedia.org/wiki/Low_Earth_orbit#Human_use The delta-v needed to achieve low earth orbit starts around 9.4km/s. Atmospheric and gravity drag associated with launch typically adds 1.5–2.0 km/s to the delta-v launch vehicle required to reach normal LEO orbital velocity of around 7.8 km/s (28,080 km/h). It doesn't break those out, unfortunately.