From one of the MSN messenger help pages, designed to explain to you why you might be experiencing slow transfer rates in MSN messenger:
Your connection speed depends on the type of Internet connection you have. If you use a dial-up connection to the Internet, your connection speed is slower than if you use a high-speed connection.
So, translated, they’re saying: “If you use a connection which is slower than a faster connection, then your connection will be slower than the fast one”. Genius!