Be wary of Earthlink. They use PPPoE (Point to Point Protocol over Ethernet), basicaly turns your DSL into a dial up style of service, you are not connected till you click a connectoid and enter a username and password. Your performance may vary.

The biggest problem with PPPoE is it adds to packet size so depending on how fat a game makes its packets you could be loosing some. Adjust your MTU size to 1200 or lower is recomended. If you have a router then the PPPoE software that is required can be handled by the router but you will likely still suffer some MTU problems so you will need to adjust them on both the router and the PC.

We have had massive headaches trying to get PPPoE setups to work with our VPN product (CheckPoint SecureClient) as PPPoE adds a virtual adapter to the network stack and gets confused once the SecureClient software is installed. Getting a third party router to handle the PPPoE package is our only solution but it is problematic.

I have no idea if it will even affect the performance of games but many have complained about streaming media performance with PPPoE since it has a tendancy to fragment packets. Adjusting MTU seemes to help.