Gta 4 problem (lagg)

So,I played gta 4 on this computer with win xp,on high settings,and it was not lagging at all.
Now,on win 7 when I install it,it laggs veryy much on minimal settings,resolution..It lags every 5 seconds,and screen just stops for next 5-6 seconds.
I intalled that 1.0.04 patch that should fix this problem,but when I install it,I cant open the game.Game window never opens.
I tried to reinstall the game few times.So after that it is still lagging,and if I install the patch,I cant open the game again.

Is it possible to play the game without anoying lagg that makes game impossible to play?

nanoextreme said:

So,I played gta 4 on this computer with win xp,on high settings,and it was not lagging at all.
Now,on win 7 when I install it,it laggs veryy much on minimal settings,resolution..It lags every 5 seconds,and screen just stops for next 5-6 seconds.
I intalled that 1.0.04 patch that should fix this problem,but when I install it,I cant open the game.Game window never opens.
I tried to reinstall the game few times.So after that it is still lagging,and if I install the patch,I cant open the game again.

Is it possible to play the game without anoying lagg that makes game impossible to play?

No, GTA 4 needs a quad core and something similar to a 4890 with plenty of RAM - 4GB DDR3 1333MHz+. Otherwise don't buy it.