Of all the satelite services I've seen, download is done through the satelite, and upload is done through 56k. This might have changed. But they can still claim that it's 4 times faster because when you're browsing the net, you don't send much, just requests for pages, and there's more downloading.
Games are played by sending small amounts of data (called packets) several times a second. Thus, the key here is ping, not download capability. Ping is the time it takes for you to send a small packet to the server, and receive a response. So the lower the ping, the least amount of lag you get (provided you don't have a lot of net loss).
What I suggest doing, is talking to the people, and see if you can find out what kind of ping range you're expected to get (obviously if you try to connect to a server in Europe the ping will be a lot higher). If you can't get them to talk about it, then see what you ping with your 56k, then try the satelite.
In all honesty it probably won't be much better. It will give you some good download speed on the net though.