HELP!!! Advise needed

i know my com is a little outdated and i've tried playing NBA 2k9 on my PC
it lags and is very slow.
Here are my com specs
Microsoft Windows XP
Professional Service Pack 3
Intel Pentium 4 2.40GHz,512 MB of RAM

I know this is sux but can you guys tell me which part must I upgrade or do i need to change the whole thing?

may we also see your vid card and btw you really need a new processor since your only running on a single core

You really need to upgrade your ram, too.

from the looks of it, it looks like you need a new rig... you should have looked around for the min required specs... anyway, just off the top of my head I think it is something like this: P4 3Ghz/1Gb for XP/Nvidia 6600.. I spent barely $400 to get an el cheapo rig that performs well. I only experience lag with the game when I'm pushing everything on high and the filtering is at 8x... 4x works fine for my el cheapo rig.

My vid card is Nvidia Geforce 6200
so from the looks of it I need a new processor, and upgrade my RAM?
What specifications would you guys recommend so there will be completely no lag?
I want to play this game without lag
Thanks

I recommend you buy a completely new rig as a new processor (dual or quad core) will require a new mobo, your ram should at least be at 1gb since you're on xp but I personally recommend 2gb or even more. Your vcard should be geforce 6800 series and above (8600/8800, 9600/9800 series are recommended) or ati 3000 series and above (ati 4000 series is recommended).

With that kind of hardware, you can probably play at high settings without lag.