Hey!
Have you played the Crysis 2 multiplayer demo yet? If not, do it! It's an awesome game, i'm having more fun right now than with CoD4.
And it does have pretty low system requirements - on "hardcore", highest graphics level, it runs better than Crysis 1 on next to highest settings on my rig.
See you there!
BTW: I'm no longer lagging! New 6mb net!