A surgical stapling system, comprising: a shaft comprising a proximal end and a distal end; an end effector extending from said distal end of said shaft, wherein said end effector is movable between an open configuration and a closed configuration, and wherein said end effector comprises: a frame; and an anvil extending distally from said frame, wherein said anvil comprises a longitudinal row of forming pockets (124p, 124d); a first staple cartridge assembly attachable to said end effector, comprising: a first cartridge body comprising a first longitudinal row of staple cavities; and a plurality of first staples removably stored in said first longitudinal row of staple cavities, wherein each said first staple is comprised of a bent wire, and wherein each said first staple is aligned with a respective one of a first plurality of said forming pockets (124p, 124d) when said end effector is in said closed configuration; and a second staple cartridge assembly attachable to said end effector in lieu of said first staple cartridge assembly, wherein said second staple cartridge assembly, comprises: a second cartridge body comprising a second longitudinal row of staple cavities; and a plurality of second staples removably stored in said second longitudinal row of staple cavities, wherein each said second staple is formed from flat stock, and wherein each said second staple is aligned with a respective one of a second plurality of said forming pockets (124p, 124d) when said end effector is in said closed configuration; wherein the first plurality of said staple forming pockets (124p, 124d) and the second plurality of staple forming pockets (124p, 124d) are the same; and wherein said first staple cartridge assembly comprises staple drivers, each staple driver comprising a cradle configured to support a crown of a first staple and a cam configured to be engaged by a sled of the first staple cartridge assembly, whereby the sled and the staple drivers are configured to push said first staples out of said first staple cavities, and wherein each said second staple comprises an integrally-formed staple driver comprising a cam surface configured to be directly engaged by a sled of the staple cartridge assembly to push said second staples out of said second staple cavities. a shaft comprising a proximal end and a distal end; an end effector extending from said distal end of said shaft, wherein said end effector is movable between an open configuration and a closed configuration, and wherein said end effector comprises: a frame; and an anvil extending distally from said frame, wherein said anvil comprises a longitudinal row of forming pockets (124p, 124d); a frame; and an anvil extending distally from said frame, wherein said anvil comprises a longitudinal row of forming pockets (124p, 124d); a first staple cartridge assembly attachable to said end effector, comprising: a first cartridge body comprising a first longitudinal row of staple cavities; and a plurality of first staples removably stored in said first longitudinal row of staple cavities, wherein each said first staple is comprised of a bent wire, and wherein each said first staple is aligned with a respective one of a first plurality of said forming pockets (124p, 124d) when said end effector is in said closed configuration; and a first cartridge body comprising a first longitudinal row of staple cavities; and a plurality of first staples removably stored in said first longitudinal row of staple cavities, wherein each said first staple is comprised of a bent wire, and wherein each said first staple is aligned with a respective one of a first plurality of said forming pockets (124p, 124d) when said end effector is in said closed configuration; and a second staple cartridge assembly attachable to said end effector in lieu of said first staple cartridge assembly, wherein said second staple cartridge assembly, comprises: a second cartridge body comprising a second longitudinal row of staple cavities; and a plurality of second staples removably stored in said second longitudinal row of staple cavities, wherein each said second staple is formed from flat stock, and wherein each said second staple is aligned with a respective one of a second plurality of said forming pockets (124p, 124d) when said end effector is in said closed configuration; a second cartridge body comprising a second longitudinal row of staple cavities; and a plurality of second staples removably stored in said second longitudinal row of staple cavities, wherein each said second staple is formed from flat stock, and wherein each said second staple is aligned with a respective one of a second plurality of said forming pockets (124p, 124d) when said end effector is in said closed configuration; wherein the first plurality of said staple forming pockets (124p, 124d) and the second plurality of staple forming pockets (124p, 124d) are the same; and wherein said first staple cartridge assembly comprises staple drivers, each staple driver comprising a cradle configured to support a crown of a first staple and a cam configured to be engaged by a sled of the first staple cartridge assembly, whereby the sled and the staple drivers are configured to push said first staples out of said first staple cavities, and wherein each said second staple comprises an integrally-formed staple driver comprising a cam surface configured to be directly engaged by a sled of the staple cartridge assembly to push said second staples out of said second staple cavities.