The best of them use a modem connection and are pinging around 250. It's mostly a matter of how well, and how intelligently, you play. Now, to be fair, I did not say that differences in ping are completely meaningless. People with low latency have an advantage over those with high latency. Then again, people who play six hours a night have an advantage over people who play six hours a month.
Mousers normally have an advantage over keyboarders.
People with Pentium II computers had better have an advantage over people with 486 computers. There's one big difference, though. People don't whine about those other things. It's the subject of at least one person's inability to get into first place, or even a single frag, on almost every deathmatch I've ever played. We all need to grow up.