Game geting stuck

Hi, I just formated my PC and reinstalled everything. Now when I started to play Deus Ex on multiplayer, it started to lag. If I start running I would stop suddenly and could see a couple of frames pass by and then return to normal for like 4 seconds. The same cycle goes over and over again.
I have a cable internet connection and ping is also like 124 in the game. Moreover, my computer and graphics cards for far better than what the game requires.
Then what could be the cause for the problem,..
Any suggestions,..

have you insalled latest patches/fixes?
I’m not sure how it could lag, you’ve got decent RAM, nice CPU good Motherboard and a pretty decent graphics card…i wonder…

Does this happen in every game?

also have you got the latest drivers for your graphics card/other hardware?

Yes I have the latest driver Nvidia 78.XX something.
I tried Doom3 and NOLF and they run fine in Multiplayer mode. Deus Ex also runs fine in single player mode. Only the Multiplayer has the problem..
I don’t think the game has any patches but, just in case i will check out with the official website.
One more thing could it be because i have installed a crack/noCD for the games.