Canon Pixma iP4200  

Urgent help please.

This printer normally connected through USB to pc running Windows XP in room 1.
2nd wireless pc running Windows 7 Ultimate 64bit in room 2.
Connected printer through USB on Win 7 pc and windows updated drivers ok and everything printing ok.
Then re-connected printer to XP pc ( in different room ) and set up printer and file sharing.
When adding printer wirelessly to Win 7 pc the windows update cannot find any drivers for this model and yet it does when running through a USB connection!
Can anyone tell me where on the Win 7 pc I can locate the drivers that were installed when printer was connected via USB or how to get around this problem? Drivers that can be downloaded from internet seem not to have an INF extension which Win 7 requires for installation.

May be being dense but can you tell me what I should be doing?

Thanks guys!

None of those tips worked previously but pleased to say that I managed to get it fixed.

Devices and Printers>Add Printer>Add Local Printer (I had been trying to add in network)> scrolled down and found the printer in the other pc and then followed the install instructions where Windows update found the model!

One day I will get my head around Windows 7 and then, and only then, will I persuade my husband to upgrade! :)