is LanCard 64K?

hello guys,

I am little confused about the Lan Card stuff. We know that a normal lancard can support upto 64kbps of data during transfer. Now why is that when I download lets say a virus definition or anything else which is already located on my servers cache, speeds up to 1 Mb, when it can only support upto 64kbps.
thankyou, do let me know.