Printing from Vista Home (Laptop) to XP Pro (PC)

My wife recently purchased a new Compaq Laptop, it has Vista Home as the OS. We have a wireless LAN.

I have connected to 2 printers on an XP Pro PC (one is an Epson/other is Lexmark)they have installed correctly (??) but when my wife goes to print to either she is unable to.

If we connect to the XP Pro pc (\\10.1.1.6 or \\'name') it prompts for login and password, once these are entered its fine and prints with not a worry.

Now if I print from another XP Pro PC it just prints, if I connect ot the XP Pro PC with the printers it just opens the folder view, it doesn't prompt for the login and password.

So why is the Vista Home Laptop requiring it?

They are all in the same WORKGROUP.

Any ideas?