Most artwork will print acceptably from a150dpi file at full print size. Hi resolution photographic prints should be 300dpi. When in doubt please try to deliver the largest file you can.
If files are being sent directly to print, they should be in .eps, .tiff or .pdf format. We can also use any sort of adobe file (.ai, .psd, indd, etc. - up to version CS 5). Files that are not print ready may require an additional charge for design or setup.