Okay, here goes a really stupid question.....

I am pretty stupid on most computer stuff, so I have a issue to ask you guys since from what I have read you know more then me. I recently moved from a house with 3 comps connected by a router. It was already there so I just plugged in and everything worked fine. I now am living with my girlfriend and we each have computers. Our internet and cable TV are all supplied by my phone company. From what I can tell, their modem feeds into a ?switch?, and that feeds both of our computers and the TV top box. Is this good?? Should I get a router? I have absolutely no idea what these things really do, other then allow computers to use the same internet connection, but it seems that this switch does the same thing. Speed is also an issue, as we both play online games and wish for the least amount of lag possible, if we are both playing at the same time. Hopefully someone can help me.

Zo