Here's another idea -
What kind of a ping do you have? you can have the fastest connection in the world, and also have a slow ping. Playing Everquest (from the client) does not require a fast connection, but does require a fast "ping". Believe it or not, modem connections usually have the best pings.
Anyways, here's something I've been using for years now, that helps optimize any type of connection.
http://www.speedguide.net/downloads.php (TCP Optimizer)
Again, if you want to learn more about all this ( and you should) I found this link very helpfull
http://cable-dsl.home.att.net/
This is stuff made easy for the Windows users - Linux users do things the hard way
EDIT;
Another thing;
Cable-internet users share bandwith with Cable-TV viewers - a lot of Cable-ISPs exploit this to a point that when the viewer traffic gets high (usually at night), it begins to slow down your connection, sometimes to a crawl.