8 gig iPhone was the original iPhone. The 3G iPhone was the second version that could run on At&t's faster internet service.
I personally would strongly recommend finding a different phone...unless you would like to share company with jerks like the other guy that answered your question.
iPhone 3G is not new. iPhone 3Gs is. 3Gs comes in 16 and 32gb sizes. Search yahoo answers for the difference. This question has been asked several times and has been answered thoroughly!