what monitor resolution are you running? what do you use your comp for? if gaming, what games do you play?
obviously answer would be another gtx 260 core 216 in sli since you have a sli capable motherboard i suppose.. along with that is a different psu to help power your system.. but only if your monitor calls for it..
Oh and i do everything inclcuding gaming, call of duty 4 , crysis, GRID etc