Setting up a cross-platform network printer

I got a new Epson Stylus SX415 all-in-one (printer-copier-scanner) from Santa Claus which was nice as my 7 year old Epson Stylus 830 was on its last legs. Wonder how he knew?
Anyway, I set it up on my MacBook which was very easy using the install CD although it did take almost 30 minutes to install what seemed an inordinate amount of stuff for which I was forced to repeatedly agree to EULAs.
After this, though, it worked fine.
During the setup, I made sure the "Share this printer on the network" checkbox was indeed checked.
Next, making sure my Epson SX415 was hooked up to the Mac and switched on, I went to my EeePC901 where I have Ubuntu Karmic installed.
Here, I went to
System>>Administration>>Printing>>Server>>New>>Printer
and it started searching for available network printers.
Very quickly it found my Epson SX415. So, I clicked on it and that was it. Very easy.
Now, my Dell 4550 with Windows XP. Being Windows, this wasn't quite as straightforward. However, the only additional step was that I had to download and install Bonjour for Windows.
This put a Bonjour icon on the desktop which when clicked allowed me to choose the Epson SX415 as an available network printer.
I did the very same on another (newer) Dell desktop running Vista without any problems.
Strangely though, on a fourth Windows computer (Vista, Dell), the printer could not be accepted as I kept getting this error towards the very end of the (relatively short) procedure:

You do not have sufficient access to your computer to connect to the selected printer

Both Apple and Microsoft have published "solutions" to this problems which are quite different. Unfortunately, neither works for various reasons which I'm not going to outline here.
However, it does allow me to once again understand why I will never consciously go back to using Windows.
Anyway, 4 out of 5 isn't bad!