lou_do,
The cable companies infrastructure is based on a 100MB per neighborhood loop, so if everyone on that loop has cable internet, you will be limited (bottlenecked, neighborhood wide) to 100Mb total, at some point they are crammed into the cable companies CO, a bad thing if half the neighborhood is a warez/slingbox monkey, cable companies use what is called edge service (a form of caching) to mitigate the performance issues.
FIOS otoh, would be different in that the bottle neck would not be limited in that way, so no matter what the people around you is comsuming bandwidth-wise, you won't be affected at the neighborhood loop (because there is no local loop limited to 100Mb, the limit, if any would be at the CO, which has FAR greater capacity than 100Mb loop).
This is was/is a selling point on DSL, since it is a dedicated connection (like FIOS), otoh, cable internet is NOT dedicated (that is why one person with concast cable (for example) might get great speeds, while someone else with the exact same setup in a different neighborhood gets crap speeds) and before cable companies used encryption, one could get into a neighbors unfirewalled (at one time very common) computer, look at their shares, print to their printers, you could even change your MAC addy on your interface and pretend to be the gateway sending spoofed arps..which is why cable kind of took off a bit slow, security conscience people did not like pre-encryption cable internet, and why dsl hung in so long...anyhow, hope that helped.
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