How to Enable AirPrint Service on Windows 7/Vista/XP (32-bit/64-bit)

AirPrint is a major feature of the iOS 4.2 upgrade but is limited to only eleven printers.

Now thanks to a simple tweak from elpamsoft.com, Windows users can use AirPrint with any printer on the same Wi-Fi network as their iPad.

1. First, ensure your printer is in a working state on your Windows PC.
2. Make sure you have iTunes or Bonjour Printer Services installed.
3. Download AirPrint Installer 1.3.
4. Run the program and you should see this screen.

1. Ensure Service Startup is “Auto” and set a password or check “Allow Blank Password”.
2. Click “Install AirPrint Service”.
3. Share your printer.

Open “Printers” in the Control Panel, right click on the printer and click “Printer Properties. Click the sharing tab and share the printer.

1. Make sure any firewall software is set to allow AirPrint.
2. Now attempt to printer a document/photo from iOS device.

1. Your printer should show up when you tap on the AirPrint icon. When you tap on the printer, you should get a pop up asking for your username and password, it will be whatever you entered in the AirPrint Installer.

*If your having problems with the iOS device discovering your printer, try rebooting your PC or restart the Bonjour & AirPrint service by going to Start > Run > (type) services (Click OK) > Right Click “Bonjour Service” > Click Restart. (do the same for AirPrint Service).

Cancel Printing or Check Status

If you would like to check the status of the print job or cancel it, double-click the home button, tap the Print Center icon, then select a print job or tap Cancel Printing.

Courtesy of http://ipadhelp.com/ipad-help/how-to-enable-airprint-for-windows-and-use-any-printer/

AirPrint on a Mac
Enabling AirPrint on a Mac is simple, here is a step by step guide.6

Update1: How to Enable AirPrint (Wireless Printing) on Mac OS X 10.6.5?
Update2: Download AirPrint Installer for Windows 7/Vista/XP (32-bit/64-bit)