i have 1gb vga card of ati radeon hd5450 and 4gb ram and dual core 3.0 E5700 processor.can my system support heavy games such as GTA 4?CAN I PLAY OTHER HEAVY GAMES?
You can, but they're not gonna run very well. Your CPU and RAM are adequate enough but your GPU is going to be a serious bottleneck in your rig. It all depends though, for example what resolution you're gonna be playing at, do you want to play at max settings?, do you mind a little lag? ect.
The HD 5450 is mainly used for media computers so as to watch movies on for example. If i'm correct the HD5xxx series graphics cards begin at gaming with the HD5670 and up.
With the specs you listed i would suggest to upgrade your GPU if you have the money
Your CPU should be relatively fine. The big determining factor for PC gaming is the video card. The 5450 is really not a gaming card. It is good for desktop apps and multimedia. You could get away with some light gaming especially older games. Not so sure about GTA4, it might have a hard time with it especially at higher resolutions.