i have the below system config.:
intel pentium 4 3.0 MHz
motherboard: Gigabyte GA-8IP775
Ram: 1 G
H. D.D: 120 G (western digital)
Directx:10.0
VGA: AGP XFX GeForce 5200 (128 M DDR)

the game (Need for SPeed - Pro Street) started fine but when the race count down began everything when so slow, i closed everything running in the backgroud in cluding the antivirus (NOD32); i even tried it on XP instead of the Vista that i am using right now but with no luck!

did anyone used XFX Geforce 6200 in the below site to run the game with no problems? Many thanx!

http://www.xfxforce.com/web/product/listConfigurationDetails.jspa?series=GeForce%26%238482%3B+6200&productConfigurationId=1050

if no, what is the minimum AGP geforce or ATI card that i can buy to let me run the game smoothly?

The 6200 is a relatively weak GPU. With that being said, THIS card would be a much more worthy upgrade to your current system which by the way isn't all that bad. The card I linked you to is $130(only $100 after rebate), but will allow you to play many more games. Everything from HL2 to Oblivion will run on this card @ high settings!

thanx man 4 ur reply..i will definitely take it in consideration.

I suggest you consider something other than the 6200 also, I believe it only has 64MB of dedicated memory, and shares your system's ram, which isn't ideal.  I had a great time with an XFX 7600GT, they are around $80 now, and I could even play crysis with it on med/low settings with decent framerates.

Keep in mind also that ATI plans to release a 3850 for AGP. That would by far be the best purchase that can be made, but I don't think there is a release date set for it yet =(.