@vaibhav_jain
No way you can play GTA 4 with PS2
, also none of the games you mentioned. It meant to play games like GTA:SA , RE 4 etc.
So better option will be a Graphics Card. For 6k,you'll get a Palit 9800GT. But make sure you have a better PSU to handle that card.
Please dont go for eco edition. Its underclocked and not meant to play games at full glory even @ 1280x1024. A plain 9600GT will beat it. So you're choice will be :
Palit 9800GT 512MB DDR3 - 5.5k
Palit 9600GT Sonic Edition 512MB DDR3 - 5.5 k
Palit HD4850 512MB DDR3 - 6.2k
Zotac 9800GT 512MB DDR3 - 6k
Just choose the right one. if you dont have a power supply to handle them, just go for this combo :
9600GT 512MB DDR3 - 5k
Powersafe Silver 500W - 1.2k
Or simply go for HD4670 512MB GDDR3 (4.5k) ones from Sapphire,MSI.(Personally i donn't recommend this for you as your budget looks good for a healthy upgrade)