Remote printer not working on Vista

I have a dual-boot desktop PC (Intel duo-core, Abit mobo, etc.) running Vista Home Premium in one partition and XP Pro in another. The primary use of the PC is via Vista, the XP partition is mainly for compatibility issues (games, mostly) with Vista.

I have an All-In-One Lexmark X2350 inkjet printer attached to the PC via a USB port, installed on Vista as local and working with no problem. I also have 2 Dell laptops running Windows XP (MCE 2005), all three computers on a wireless network through a Netgear router and visible to each other. The a/v software is Kaspersky Internet Suite 2009.

I have tried to install the Lexmark printer on each laptop to run remotely through the desktop PC when running Vista, but although I can set up a port on each laptop to output prints to the desktop, nothing will actually print. I can see a "Remote Downlevel" message appear for a split second in the Lexmark print queue, but no prints get sent to the printer.

Now, when the desktop is booted up into XP, the laptops can be configured to output prints from the desktop with no problem, exactly as it was before I upgraded to Vista. Unfortunately I prefer to use Vista and if someone in the house wants to send something to print, at the moment I have to restart in XP for this to be possible. I have tried everything but this appears to be a Vista problem; here are the settings:

1. Installed printer is set to Shared.
2. Installed printer has no password protection for remote printing.
3. All 3 computers can see each other's shared files, so network is OK.
4. Laptops have printer port allocated to \\<desktop name>\<printer name>.

As a last resort, I switched off the Kaspesrky software on all machines, but it made no difference. Any assistance would be greatly appreciated.