"The Broadband Cable Modem Speed Situation
To get going, it's important to address the issue of cable modem access speeds, which is probably why you're interested in broadband service in the first place.
Many cable companies and Internet service providers argue that cable modems are as much as 100 times faster than a dial-up Internet connection, running at an ultra-fast speed of 5 million bits per second (mbps). In theory, it's possible. But a more realistic speed is 1 mbps, or about 20 times faster than a typical 56,000-bits-per-second (kbps) dial-up connection.
Still, that's quite a leap in performance, an upgrade well worth the investment. Web pages that can take minutes to paint with a dial-up connection will pop up instantly with a cable modem. If you frequently download large files, such as video and audio clips or software, a cable modem will make life much easier. Because cable modems are always on -- that is, constantly connected to the Internet -- there's no need to dial in to an Internet service provider (ISP). Simply click on your browser and you're on the Internet. No more waiting, no more busy signals."
In short, yes, 6 mbps is quite fast, but not a realistic speed.
(By the way, "Mbps" stands for "Megabits-per-second," the prefix "mega-" referring to a million.)