After reading an article about which players were being sent to the pro-bowl by the 49ers and which ones should have been sent. I think its fairly obvious that the two positions we need to upgrade at are WR and OL.
Mike Iupati was the only consistently good player on the OL this year. Staley and Goodwin were serviceable. Rachal, Snyder and Davis are horrible. If we can put together a unit that will not be last in the league in sacks given up I think it would work wonders for Gore and Smith.