have you checked the print settings in illustrator? if you set it to rasterize at a low res then no matter what you print it will be pixelated. Its normally ok by default but maybe something messed it up? its worth a look anyway, its in preferences.
THis problem happend right away out of the box. I just installed the software and printed and thats it. It even prints the text pixelated when i create outlines around it in illustrator.
I returend a canon i9900 right before this one because it was doing the same exact thing.
If you had the same problem with the Canon printer that you have with the Epson printer, then the problem is most definitely not your printers. You need to sit down with someone who understands Macs better than you do and go through your installation step by step.