Ok run AirPrint on your Pc and activate either the 32 or 64 bit one (it runs as a service) once you've done that go to windows firewall and add the program so it will be allowed through the firewall. this is done by adding AirPrint.exe in program files/AirPrint Now you have two options here either activate the GUEST account or set a login password to your windows account. If you activate the guest account then all you need to do when windows boots is click your login icon.
So to the printer. This has to be the printer that is connected to your Pc usually by USB. Go to printers and right click on the printer and select delete, once it's deleted just add new printer and reinstall the driver (make sure you select USB AND NOT LPT1). Windows will remember the driver and will ask you if you want to keep the existing driver, just click yes. If it ask "do you want to share this printer" select yes, if not after the driver has reinstalled right click and select sharing click the box to share the printer, then ok.
That should be it, if you see a little lock icon on the printer name on your iPad you've probably not allowed AirPrint through your firewall correctly.
This works in the same way we used to share printers on a network before printers came with a network card built in so this will only work as long as the Pc is switched on.
If you activated the guest account then you won't get a username and password login request if you set a password on your windows account then a username and password login request box appears on your iPad, just use the same name and password as you would to login to your windows account.
If you happen to have a networked printer and a laptop that connects to your network wirelessly and uses the networked printer, AirPrint works very well that way too, I use it that way very successfully
Hope that helps Rich