home networking accessability

I am setting up a home network. I am running 3 different macines w/ 3 dif operating systems,98SE, winme, XP. I am having trouble accessing from the XP machine to both 98SE & ME machines. the XP machine sees the other drives, but access is denied. then the 98SE & ME machines work fine, but neither of them sees the XP machine. I have disabled the firewall w/in XP but the router has 1