Helpp w/ fantasy football please?

i have too many rb's on my team and i dont know which ones to keep and which ones to drop. these are all the rb's on my team: willis mcgahee, ray rice, jamal lewis, julius jones, cedric benson and felix jones. im dropping jamal lewis for ray rice but i dont know who to drop for julius jones. i have a feeling that felix jones will improve so i want to keep him. should i drop cedric benson for julius jones? if i do, that still leaves me w/ 4 rb's(rice,mcgahee,felix jones and julius jones) should i also drop mcgahee since ray rice might get most of the rushes? pls give me your advice/opinion. thanks!