Go with dingy he's right.
Here's my summary of connect-related issues, from a year of reading people whine about it and flying here and on brand-W.
A. Things that will screw up your connx mighty fast:
1. A "Winmodem" -- CPU-driven compression has a problem with online games, as both need the processor at about the same time (AH will use your CPU at 100%, Winmodem will want some of that too, it won't get it, and the results are ugly). To oversimplify, if you cannot use your modem with DOS, you have a problem. This is serious.
2. On a TNT card (and I imagine for others) If you've got Vsync off, make sure your drivers are set to render 0 frames ahead.
3. Packet loss. This is your number one enemy. Think of every lost packet as a microwarp.
4. Wildly variable connection lag. This will cause all kinds of jumping around, late hits, offsides and the like.
B. Ping Times and Bandwidth
I've been in Europe, connecting across a LAN on academic networks. These nets are heavily used (read oversubscribed) during working hours and amazingly fast off hours. So, I've been able to experience with the same connection, >1000 ms with nasty packet loss, 700 ms steady with minimal loss and up to 160 ms ping times.
1.
Bandwidth doesn't matter. Those who brag about their cable modems will have great bandwidth, and might be able to receive video on their computer; they might (probly) also get a faster ping time than a modem. But if their ISP has oversubscribed their services, you're gonna see nasty problems, packet loss, narrow bandwidth, and the like, especially at peak usage hours.
Again, I've seen my PC get up to 100k/sec streaming video on weekends. But at 1:00 PM on a wednesday afternoon, I'll get 100 bytes/sec and I'm lucky to get a single web page without losing the connection.
2. Lag
Yes, lag makes a difference. It comes in two flavors -- server lag and connection lag. Server lag is more or less static, and reflects the time it takes for the server to process information and spit it out again. I t might increase with users online. Connection lag is the time it takes for the data to travel from the FE to the server and back. This is more or less related to your ping time. There is a difference to playing with 700 ms and 100ms, and there is a difference to playing against someone witha 700ms and someone with a 100ms connection. The higher your lag, the older the information you receive in your FE world; so e.g. the A/C charging behind you is closer than it appears, and the one you're attacking will see you farther away than you really are. In other words, you need to adjust your reaction times and tactics to fit your lag times. From my experience, switching between 700 and 200 ms lag can be disorienting -- your reflexes are all off.
So, in summary, modem or not, high ping or low, what's key is to get a steady stream of data flowing at a constant speed.
Dinger