The drivers and software on most Canon web sites are supported on 10.6. So, for the printing, as long as you have the printer driver version 10.26, then there should be no need to run any Apple updates.
However the Canon driver will only work if you have the MX320 connected directly to your Mac via USB or to an Airport device via its USB port. If you have the printer connected to a Windows computer or a 3rd party print server/router, then you will not be able to use the Canon drivers.
If you do have the printer connected directly to the Mac via USB, then there may be something wrong with the cable. When you select to Add the printer and have the Default view open, do you see the MX320 in the list? If not, then this can indicate the cable is at fault.
If you do see the printer in the list and select it, does the Print Using menu automatically change to 'Canon MX320 series'. If not, then there may be some conflict within your Mac and you will need to do some cleansing.
If you can give more detail about your symptom then it will be easier to guide you through the fix.
Pahu