PIXMA iP1800 is a good cheap inkjet printer. And it work in Ubuntu very well.
1. Connect printer to USB, switch it on, open it and insert cartridges.
2. Now you can see a message in top right coner on your screen. It tell that Canon iP1800 was connected but driver was not found. Press the button for add printer to system and use the standart text driver.
3. Download iP1800 driver
4. Install packages by double click.
5. Go to System -> Administration -> Printing, select iP1800 and press the Change button.
6. Select /usr/share/cups/model/custom/canonip1800.ppd
7. In the preferences window press Apply.
That's all. Your Canon iP1800 is ready for work.