Excellent, thorough, yet easy to understand article about File/Printer
Sharing in Vista. Includes details about sharing printers as well as files
and folders:
http://technet.microsoft.com/en-us/library/bb727037.aspx
For XP, start by running the Network Setup Wizard on all machines (see
caveat in Item A below).
Problems sharing files between computers on a network are generally caused by
1) a misconfigured firewall or overlooked firewall (including a stateful
firewall in a VPN); or 2) inadvertently running two firewalls such as the
built-in Windows Firewall and a third-party firewall; and/or 3) not having
identical user accounts and passwords on all Workgroup machines; 4) trying
to create shares where the operating system does not permit it.
A. Configure firewalls on all machines to allow the Local Area Network (LAN)
traffic as trusted. With Windows Firewall, this means allowing File/Printer
Sharing on the Exceptions tab. Normally running the Network Setup Wizard on
XP will take care of this for those machines.The only "gotcha" is that this
will turn on the XPSP2 Windows Firewall. If you aren't running a third-party
firewall or have an antivirus/security program with its own firewall
component, then you're fine. With third-party firewalls, I usually configure
the LAN allowance with an IP range. Ex. would be 192.168.1.0-192.168.1.254.
Obviously you would substitute your correct subnet. Refer to any third party
security program's Help or user forums for how to properly configure its
firewall. Do not run more than one firewall. DO NOT TURN OFF FIREWALLS;
CONFIGURE THEM CORRECTLY.
B. For ease of organization, put all computers in the same Workgroup. This
is done from the System applet in Control Panel, Computer Name tab.
C. In Vista, turn Password Protected Sharing ON. Create matching user
accounts and passwords on all machines. You do not need to be logged into
the same account on all machines and the passwords assigned to each user
account can be different; the accounts/passwords just need to exist and match
on all machines. DO NOT NEGLECT TO CREATE PASSWORDS, EVEN IF ONLY SIMPLE
ONES. If you wish a machine to boot directly to the Desktop (into one
particular user's account) for convenience, you can do this:
XP - Configure Windows to Automatically Login (MVP Ramesh) -
http://windowsxp.mvps.org/Autologon.htm
Vista - Start Orb>Search box>type: netplwiz [enter]
Click on Continue (or supply an administrator's password) when prompted by
UAC
Uncheck the option "Users must enter a user name and password to use this
computer". Select a user account to automatically log on by clicking on the
desired account to highlight it and then hit OK. Enter the correct password
for that user account (if there is one) when prompted. Leave it blank if
there is no password (null).
D. If one or more of the computers is XP Pro or Media Center, turn off Simple
File Sharing (Folder Options>View tab).
E. Create shares as desired. XP Home does not permit sharing of users' home
directories or Program Files, but you can share folders inside those
directories. A better choice is to simply use the Shared Documents folder.
See the first link above for details about Vista sharing.