The speed of your connection has nothing to do with the ability, or inability, to connect to Xbox Live. It will impact your gameplay, but not as much as you might think. I'm assuming you have the 768k down and 128k up package? According to Microsoft, that is sufficient to play online, but you will not be able to be the host. With online gaming, it all comes down to latency and not speed. You can have the fastest connection in the world but with high latency, you are still going to lag.
Anyway, like I said, with your current connection you should still be able to connect to XBL. If you can't, there is something wrong and a speed upgrade won't help.
Edited by Spyderturbo007, 13 January 2011 - 01:58 PM.