You can EASILY 5 box on a basic DSL connection. Remember, some people still use 56k modems to play.

The issue is upload bandwidth. Assuming an 8 mbit (roughly 1 MEGABYTE) per second upload and download, you could run 10 - 15 boxes at once NO problem. Of course most connections are desync, limiting the upload bandwidth. Figure 56k (.056 megabits) per box as a good rule of thumb.

So a 2 megabit up DSL would give in theory about 35 connections. In practice it will give maybe half that assuming off peak hours.

Under 200 ms pings are preferred for boxing. 500+ starts to get problematic and 1000+ starts to break follow on the ground just running around.