Not so. Both AirPrint for Windows and FingerPrint will setup the PC as an "AirPrint" host and display printers attached and shared by that PC on iDevices. My "non AirPrint ready" HP printer shows on my iPhone at home using FingerPrint.
Note: The PC and iPhone must be connected to the same network (home LAN) for this to work.
Note 2: AirPrint quit working with the latest iOS5 update on the phone. I install FingerPrint and it corrected the problem.
FingerPrint is definately the better solution if you can accept the $9.99 price tag.
I have found a few ways to this, one involves FignerPrint as noted above ($).
Other options depend on which version of iOS your are running on your mobile device.
For iOS4 you can use following link, however when you get to step 5 I would modify name of service to be "AirPrintOS4" instead of "Airprint" in command "sc.exe create AirPrint..." (this will allow support for BOTH iOS4 and iOS5... next step).
For iOS5 you can use the following link,
Original source at http://iblueray.de/?page_id=209 ... translated to English...
Note the steps to (a) enable Windows GUEST account, (b) ensure local printer is SHARED, (c) open firewall for tcp/udp port 631 for airprint.exe. After I ADDED APPLICATION thru Control Panel/Firewall (browsed for airprint.exe) ... I went back under ADVANCED SETTINGS and changed from ANY port to SPECIFIC port (631)... for my PRIVATE (not PUBLIC or DOMAIN networks... but up to you).
Now my iPhone running iOS4 and my iPad2 running iOS5 can print to Windows-based printers.
Of course my MAC BOOK PRO uses a different solution which works great... MAC printers accessible from both iPhone iOS4 and iPad iOS5 ....