Bridging an ethernet connection between three wireless computers

Hey,

Up until yesterday, all of my computers were located next to my modem/router. They are all wifi equipped, but as long as I have an ethernet cable available I used that so that I could do quick file transfers and stream video over the network if necessary.

Now I've moved all of the systems to another room where I cannot use a wired connection fro the router. Since all of the systems are wireless capable, getting a connection is not a problem - but of course, wifi is somewhat brutal for local file transfers when compared with ethernet. So, I have an ethernet switch - this one, to be exact. The computers (four of them) are now connected via cat5 to the switch as well. All of the computers can see both the wired and wireless connections, but none can see each other on the network as they could when they were all wired - even though they're all connected through the ethernet switch.

Two computers are running Windows XP SP3, one is OS X 10.5.2, and another has XP SP3, Vista Ultimate x32, and Ubuntu 8.04 on it. None of them can see one another.

So is there something I'm missing to get these connected through the ethernet switch? Thanks for any help in advance, I appreciate it!