Get yourself Ping Plotter from:
http://www.pingplotter.com/download.html
(The Standard version. 30 Trail, but still works afterwards)
Do a traceroute to the actual games server IP address and see where the problem lies. If you save an image and post it here. Attached is a ping plotter image to give you some idea of what a bad connection looks like. Plus you might want to change some of the default settings in the bottom left hand corner, picture attached of settings.
Also if you post your modem signal levels here, some kind person will tell you if there's a problem with your modem or not.
http://www.cableforum.co.uk/board/12...al-levels.html