As promised, I'm replying with the answer re: how to access my home network printer without having to change my settings from domain to workgroup...
First of all, someone at Microsoft should lose their job for all of this. It's just ridiculously complicated and there is a trail of blood and tears all over the internet due to this.
The general solution that seems to work for most people can be found at the following link:
Consider It Fixed: Printer Sharing Problem in Windows Vista
Of course, the general solution did not work for me. If the general solution above does not work for you, print out the article above.
Follow each step in the general solution until you get to the part where it says:
"manually add a new Local Port as follows: \\computer_name\shared_printer_name"
If this does not work, you get an error, a security warning, etc., do the following:
0) Make sure your Windows Vista PC and Windows XP PC are both connected to the network.
1) Shut down your firewall
2) Go to your Windows XP computer
5) Type "cmd" in the box
6) Type "ipcong"
7) Write down your IP Address (example: 188.8.131.52)
8) Type "exit"
9) Start button
11) Control Panel
12) Printers and Faxes
13) Click on the Sharing tab
14) Write down the EXACT
name of the printer shown there. (Important note: for me, the printer name was slightly different from what was showing up on my Windows Vista PC after I installed the drivers per the article above.
After this, I was able to go to my Windows Vista machine where I left off from the article posted above and type the path my IP address and printer name:
Example: \\184.108.40.206\LaserJet 1200
and finally connect to my home network printer from my Windows Vista PC and start printing.