Cable modem on comcast.

Ok, I was using a cable modem, with comcast, and Have two
computers, one main on 98se and the other on 2000, the
2000 is a laptop on a station. A few weeks ago I Set the
2000 on the desk and wondered what would happen if I
pluged in the usb cable from the back of the modem, which
has a eithernet connection and a USB. I sum how mannaged
to get the 2000 to run with the 98se at the same time it
was a little slower, and I was able to play a game on the
98se and the 2000 I could surf and talk to people, It was
a fluke, but if anyone knows how I did it, I would love to
know myself. I know about the ICS, on 98se. Dont have an
extra nic card. Any other suggestions?