So, for all that I am pretty computer savvy, I have never dealt with networking before. I have 3 laptops that I use alone, plus a desktop and 2 laptops that are used by the rest of the family. We all connect to the internet using the same wireless, or wired router. The desktop is wired, the laptops are usually wireless. We also have a printer that I'm pretty sure has wireless capabilities, but I'm not even worried about that right now. My goal right now is to create a way to share files between my three computers, without allowing access to the rest of the house. I'm having some serious issues.

Computer 1: Dell Inspiron, Windows XP Home SP3, Odin
Computer 2: Toshiba Satellite, Linux Ubuntu Karmic, Thor
Computer 3: HP Pavilion, Windows Vista Ultimate SP2, Apollo

Apollo can can't make up his mind, and sometime will view files on Odin, sometimes on Thor, sometimes both, sometimes neither.
Thor can view files on Apollo, but not Odin.
Odin cannot view any other files.

Obviously, I'm doing something wrong. I think I just need to start over, but truth is, I'm flying by the seat of my pants here. Any progress at all was got by guesswork and 'just clicking on stuff', so I'm not sure where I *should* start... Any help would be greatly appreciated...