I would say you could do this trade simply because you have stud RBs for your main guys. The potential upside to Shonn Greene is higher than Jones. Jones will split carries with Charles for the rest of the year at a 50/50 split so you know where his value is pretty much locked at. Should LT go down or start to show his age, there is potential for Greene to be very valuable again. This is a big if, but you have the starters to take the risk if you want.
QB - A Rodgers, E Manning
RB - A Foster, S Jackson, R Mendenhall, T Jones, R Bush
WR - G Jennings, L Fitz, S Smith (Car), P Harvin, V Jackson
TE - A Hernandez, J Tamme