Well, the majority of your problem, is probably the game server location. 256 on cable, is more than likely because of distance, rather than bandwidth. No cable connection is THAT BAD.

If you can rule that out, make sure you aren't uploading or downloading any files while you are playing. IE: P2P apps. Make sure nobody is using these that may share your connection to the internet as well.

If a server is in finland, and you are in NY, it's not gonna be pinging well, due to sheer distance.

Just a thought.