The Canon GP200 series were sold with two different printer board configurations, at least that was the case in Australia.
The Canon printer board had PCL5e as standard and PostScript as an option. Since you were printing from Leopard, there is a good chance you had the PostScript option, although since PCL5e was also supported via the included Gutenprint v5.1.3 then you would have still been able to print without the PostScript option.
The EFI printer board had PCL5e and PostScript as standard. If you have this printer board installed, then it is necessary to input a LPD queue name of print (all in lower case). If you don't enter the correct queue name, the print job would leave the Mac but fail to print at the copier. Note that the EFI printer driver included an Adobe PS installer, which will not work on Snow Leopard. So you would have to look at using Generic PostScript for the printer model.
The other thing to note is that both printer boards provided AppleTalk - and I believe the Canon board also supported EtherTalk. Since AppleTalk has been removed from Snow Leopard, you would have to add the printer via IP > LPD. Neither board supports HP Jetdirect-Socket (aka Port 9100) or IPP.
In order to print via LPD, the GP200 would need to have an IP address. If you were using AppleTalk with Leopard, then you probably don't have an IP address entered in the GP200. But I cannot remember how you get into the setup menus for that model so you would need either to find some documentation or contact your local Canon support to see if they can talk you through over the phone.
Pahu
