Upgrade the Graphics card or CPU??

I am assuming a desktop computer?? From just a quick glance, you may very Well need to update your entire system. Does your MB have PCI express on it?

Wow, blast from the past.
Are we talking a D915GAV or a GAG?
If you could upgrade to a core 2 processor, I’d do that, but your buss speed is going to be a serious choke point.
You are limited to DDR 400/333 memory
If you have the GAV you only have a 10/100 NIC

At this point you need to seriously consider upgrading your motherboard, memory and processor to a recent chipset.

If your budget is limited you can still get a good stopgap with this motherboard:
http://www.newegg.com/Product/Product.aspx?Item=N82E168... $45.

You keep your 775 processor but upgrade G41 which gives you DDR3, PCIe 2.1 and a modern NIC.

Now the GT520. This is not a top drawer GPU. Not close. You will have to lower your gaming expectations a bit.

If its a budget issue I’d get the new motherboard I recc’d, 8gb of DDr3 1333 and a HD 7750 GPU. You will see across the board improvement, especially if you go to a core 2 processor.

PCI express available

Ya this is D915 GAV ...... Really i cant go for the upgrade...this is really one old piece of mine..........
can't a gt520 hold the issue??
b coz i dont care about waiting for installations or loading screens....
just the gameplay with high settings and no lag I want

This is the issue (bold)
As groundrat suggested, you need to upgrade your mobo

he is asking if the gt520 will run on that mobo thats it...help him i think he can

he is asking if the gt520 will run on that mobo thats it...help him i think he can