I bought Canon LiDE 20 scanner in year 2000 if I remember correctly. Somehow it is still working with Windows 7 x86.
Download the driver from canon site lide20lide30n670un676un1240uvst7031a_xpen.exe.
You will see your driver installed after running it.
Download and install the CanoScan Toolbox 4.1. Use this for scanning.
Tips: Do not use Windows Fax and Scan. Maybe you can make it work with the driver but I cannot.