Modem

I am Having problems with my computer this is what is happening:

1)When I play a game called World snooker, the game does not flow it seems to stager on the monitor.

2)I have noticed that my modem lights are continually flashing (these are flashing on Enet, U/S they are flashing even though I am not downloading ). D/S, sync and rdy stays on all the time .

3)I am connected to a wireless router, even some of these lights are continually flashing. These are Ethnet and Port 1

Any idea what is going wrong?

I need a demo copy Windows Media Centre