2 computers on a cable modem isn't going to be a problem. since the pipe is shared with other households that would eat up more (usually) then just having one other computer connected to your side. If you are looking at the game aspect of it, if you are able to send and receive data at 20k/s you should not have any problems with ping times (although routing is sometimes an issue with cable). As far as a performance hit on your system, theres really no chance of it unless you don't trust the other user, but I doubt this is the issue. Sorry if I rambled on, its getting late, and I wanted to at least get my first post on this site. Been helped so much in the last day, thought I would try to give out a little bit of info.