Barefoot Running Technique II

With the weather turning warmer, I have been running outside a bit.  Initially, I noticed my stamina running outside was much lower than when I run inside at the track.  I thought about it, and realized there was one major difference: when I run indoors, I run barefoot (in socks only).

Apparently, even with wearing minimal shoes when running outside, my form disintegrates and I run less efficiently.  I don't plan on running barefoot outside on the streets, so I need to come up with an alternative.  I may buy a pair of Vibram Five Fingers, which have received some positive reviews from runners.  Other than that, I may just have to practice more barefoot running indoors, and try to transfer the same technique to when I'm outside running in shoes.