Epson Stylus Photo Colour R300 and Intel iMac Aluminium running Snow Leopard.
The print quality is bobbins with horizontal banding (looks like it is printing in low quality mode). The menu where the print settings should be (double click on printer, click printer setup and tab drivers) is blank.
Lots of reports in the forums of horizontal lines in the output (banding) but the print heads/calibration/nozzles all fine printing from an SD Card.
There is nothing wrong with this printer or Snow Leopard, all we need to do is find the CUPS advanced print settings.
Don't install the drivers off the disk if you have Snow Leopard. Let OS X do it's thing and download the driver if it needs it. The Epson software is bobbins and lets face it, a printer with a front panel doesn't need to let anything know it is short of ink.
Using Safari Navigate to http://localhost:631, select your printer, then "Set Default Options" from the right drop down menu ("Administration").
Every permutation you could wish for is there. (Select the correct paper type, set resolution to 720x720dpi and Print Quality to Photo RPM). In my particular experience, the Epson driver provided a more lively picture than the Gutenprint, but the print quality of Gutenprint was slightly better. The printer worked slightly faster using the Epson driver than Gutenprint.
You should now be able to get fantastic printouts from an ageing printer and Snow Leopard.