What's the best graphics card for my machine?

Save your money for a new pc. Or look for a used card on ebay such as a Geforce 6800 series.

The HD 4670 1GB AGP is the most powerful video card you can upgrade to; $115.

http://www.newegg.com/Product/Product.aspx?Item=N82E168...

However, your CPU will surely cap it's performance. Thus, in the end you will be wasting money.

I would have to guess that the best "new" card in your situation would be an HD 3650 for about $63 after rebate.

http://www.newegg.com/Product/Product.aspx?Item=N82E168...

I think that would give you the best performance for the money.


Realistically speaking, if you want to play games released since 2007 you should really buy a new PC.

The best options...
http://www.newegg.com/Product/Product.aspx?Item=N82E168...
http://www.newegg.com/Product/Product.aspx?Item=N82E168...
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

I would also reccommend saving for a new pc but if you choose to take the route of a gpu only upgrade heres a choice.

Powercolor Radeon 4670 1GB

http://www.newegg.com/Product/Product.aspx?Item=N82E168...

The best option in my opinion would be the 4650 that gkay09 linked to. It would be the best match for your CPU and has GDDR3 memory on the card. Buying a card with GDDR2 really isnt a good idea as the GDDR3 cards are so much better.
The other thing i would say is if budget allows it upping the Ram on your machine to 2gb will help a lot with newer games also. There is always the option of overclocking your P4 if you fancy ?
Mactronix

I'd look for a used x1950pro agp, it was a powerfull card and will match your expectations. But saving for a new pc would far better option.

whats games u mostly play?

This would be the best for you.

SAPPHIRE Radeon HD 3850 512MB 256-bit GDDR3 AGP 4X/8X
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

Other good option is the 4670 and 4650.