I have a lithium k2 5.75 3x8 with shimano 442 square taper cranks. I want to upgrade the derailleurs /cranks and am not sure if i want to go 3x10 or 2x10. Anyway, my brother, who i got the bike from tells me its a gxp type bottom bracket but mine is an internal thread square taper and doesnt look like a gxp. Can anyone help shed some light on what i have and what will work?

thanks