I had gta4 on win vista previously, then i got Windows 7, anyhow i installed it with lots of efforts, then it ran, but it is much slow that it previously ran on vista.

anybody got any solution for this?
my configuration
Core2Duo E4600 2.4 GHz
nVIDIA 8600 GT with 1 GB Memory
2 GB RAM
I have to close down all the applications to play the game.