What equipment would I need to do this?

[mobutter]

I have a computer with cable internet that I would like to split with another computer that is upstairs and on the other side of the house. I went to best buy to see what I could do and the salesperson blasted off like 4 different things such as 400$ for wireless, or I could wire up some cable inbetween which is pretty much outta my league(time,inexperience), the third one was some telephone connection and I couldn't even understand the fourth and last thing he was talking about. I was thinking that by now, hooking up just 2 computers to the same internet connection would be cheaper than this? Anybody know what I can do??