Vista can't print to XP shared printer

The weird thing I noticed right off was that I couldn’t see any computers on
the network except my own. Bizarre, but I could call up the server by
running \\server... so , no biggie.

What we soon discovered is that we couldn’t print to the printers shared off
our printers pc. We can print to the plotter which is shared off the server
though. So, I tried to call up the printer pc through the network to no
avail. So, it seems to have something to do with the fact that I can see the
shares of the server, but not the printers pc.

Through some googling I was able to get all the computers to show up in the
network window, but I still can’t connect to the printer pc. When I
double-click the icon for the "Printers" pc, it asks for a login. But, it
accepts no logins. A handful of computers on the network will allow me to
see the shares though. Which is odd since all that stuff should be handled
by Group Policy…so they all should be the same, in theory. Nevertheless, I
get mixed results.

Check out these bizarre symptoms and see what you think:
-Can see all computers on the domain in the Network Window
-Can browse the shares of only about 25% of the computers
-All other computers on the domain can browse MY (Vista) shares and see the
printers pc shares
-Double-clicking the printer pc icon in the Network window results in a
login screen which accepts no logins, admin or otherwise.
-Was able to add all shared printers by adding them locally and then adding
a new local port to point to a network location (\\printers\HP9800).
-All test prints error out
-Restarting the Vista pc after trying to send a test print results in the
test print PRINTING. Attempting to print again after login to the Vista
machine results in another failure.
-Have no trouble printing to the plotter which is shared off the server as
opposed to the printer pc

So, there you have it. There’s obviously something going on with the domain
login that fouls things up. The bumped up security in Vista totally screws
things up from what I can tell. Being that the test prints go through fine
before I log in to the domain is definitely saying something.

I discovered that some of the computers in the office have the Guest account
enabled and some don't. I tried enabling the guest account on the Printers
PC but it still won't let me print to the printers.
Note that all the XP computers in the office can see all shares and print to
all printers. It's just the Vista machines that are getting these weird
problems.

Also, Vista seems to ignore certain portions of the SBS 2003 Group Policy.
For example, the Windows Firewall should be turned on. On all the XP
machines the firewall is on and you can't turn it off. In Vista it's on, but
you can turn it off easily. What gives there?

What do you guys think?

Thanks,
Matt Tyree