GTA IV slow gameplay!!?

So i recently purchased gta 4 had been waiting fr a long tym 2 play sum good games as i always had a prty obsolete computer and was nvr able 2 play such games. Now i gt a new 1 wid intel core 2 duo 2.9 processor, 4 gb ram and 1 tb hard disk i dunno abt d graphic card though bt still i guess a comp wid such features must b having a decent inbuilt graphic card. Ok so the problem is that after installing the game which took lots of tym its being very slow. Its xtrmly iritating nw tat even after doin so much the gameplay is so slow. I dunno wat 2 do i really wana play dis game. I searched on the net and installed all the latest patches and stuff but still its slow. Any1 got any suggestions???