A big fan of gta series like me and want to try hands in latest gta 4.
ohhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh but dont have minimum specs
don't worry here a way to roll in gta 4
first check specs needed to play it (my recommended)
xp sp(1-2) .plz dont use vista,window7 for this u will need dedicated gpu.
atleast 1.5 gb ram
video 256 mb(internal)
and hdd as required
But if have less specs than i have provided than use Game gain to stop lagging.

Now what tools u will need
1. a 3d- analyzer
2.Swift shadder 3.0

Now we began our process
1.Install gta -4
2.download and install 3d analyzer
3.download swift shadder and paste in your game install directory dont put in any sub folder in install directory.just put in root of your gta 4 install directory.
4.Now open 3d analyzer
I. click select and browse for your gta4.exe in install directory then click on open.
II. In vendor id and device id put Nividia geforcefx 5900 ultra id's

now open the game it runs but i little lagging.I personally used.
it works but if u use vista or win 7 i laggs like hell.