Vista - issue trying to access other computers that are vista on the network?

Well I got three computers all of them are networked together one of them is xp and the other two are vista but when I try to access the the vista from a vista comp it will ask for a username and password why is it asking for this and second it wont even recognize the vista comps on the network from the xp comp. Help me out because I am trying to transfer a file from one of my vista comps to another but im having this issue.
THANKS

Step 1: Open Control Panel
Step 2: Open Network and Sharing Center
Step 3: Ensure that the options of File Sharing, and Public Folder Sharing are ON.
Step 4: Ensure that Password Protected Sharing is turned OFF.

Do this on all computers.

Hope this helps,

Extensa

Also the default workgroup name in XP is MSHOME but for some reason in Vista and W7 they changed it to WORKGROUP. So go in to where it lets you change the computer name and make sure all of your machines are using the same workgroup name.

Start off just trying to use the folders that are shared by default. Like All Users Documents in XP and Public in Vista. Once you get the basic stuff to work, seems like then you can set your preferences.