You are quite right that you don't need to spend any money to get this
set up. It simply requires that you read through the instructions to set
up your Local Area Network file/printer sharing and then patiently go
through the process. It is not hard.

This link will take you through Vista networking very well:

http://www.microsoft.com/technet/network/evaluate/vista_fp.mspx

Problems sharing files between computers on a network are generally
caused by 1) a misconfigured firewall; 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.

Here are some general networking tips for home/small networks:

1. 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. If you aren't running a
third-party firewall or have an antivirus with "Internet Worm
Protection" (like Norton 2006/07) which acts as a firewall, 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. Do not run more than
one firewall.

2. With earlier Microsoft operating systems, the name of the Workgroup
didn't matter. Apparently it does with Vista, so put all computers in
the same Workgroup. This is done from the System applet in Control
Panel, Computer Name tab.

3. Create identical user accounts and passwords on all machines. If you
wish a machine to boot directly to the Desktop (into one particular
user's account) for convenience, you can do this. The instructions at
this link work for both XP and Vista:

Configure Windows to Automatically Login (MVP Ramesh) -
http://windowsxp.mvps.org/Autologon.htm

Then just set your sharing on the printer, install the printer drivers
on each machine, and you should be good to go.

Malke