Well my new Windows 8 Notebook did not install canon MP620 so easily...
Following instruction works, if your Canon MP620 is allready in your network (working with other Computers you may have):
1. Insert installation CD in your new Windows 8 computer and do NOT choose automatic installation.
2. Click on the Installation by User and choose every programm of the installation CD, except JI Network.
3. Close the installation.
4. When installed, ignore the error, that should apear telling you, that JI Network is not fitting your windows system.
5. Visit this Canon Site an install the driver at the bottom of the site (the site is in german, but you should find the canon site in english, too): Canon Network Setup und Tool
6. Make sure, your new windows 8 computer is connected by wifi or ethernet to the internet and to your home network.
6. Run this driver and follow the instructions, that means connect your Canon MP620 printer with a usb-cable.
7. Start the installation.
8. Choose the canon printer, that appears with a green ok-sign and go on.
9. The programm will now install the printer as the standart USB-Printer and Wifi-Printer at the same time!
10. Disconnect USB-Printercable and test the wifi-printing by opening e.g. Word and typing something. The printer is going to react and print your text.
11. Done !!