What OS do you have ? Are all the accounts on one pc ? are there multiple PCs ? What exactly do you mean by " files " ? do you want to network the PCs if you have multiple pcs ? Do you have a router / do you have broadband ? are all the pcs in one location, or are they on different floors ?
do you want to use peer to peer networking ?
You can use the offline files feature... All you have to do is map a network share with the credentials of the user for the other computer and make it available offline. But make sure that the workgroup names on both comps are identical. Windows XP Pro is recommended cause you can set security settings for each file/folder.