[Guthrie]

I'm on Cox high-speed in Texas. No problems with or without a Linksys router. I'm running two PCs and two TVs on it all the time.

You should have no problem using a splitter unless it's a piece of junk. Since there's only one cable coming into your house, there's going to be one or more splitters somewhere on the system even if you can't see them. When I lived in an apartment in southern California I had to use powered splitters, presumably because of long wiring runs of questionable quality inside the building. I rewired my house in Texas myself with a home networking system so I'm fairly confident in all the connectors.

Another thing you may want to do is terminate any open connectors, including those on multi-way splitters. I don't know if this really helps, but it can't hurt.