These drawing programs generate art that can be scaled to ANY size with no 
loss of quality, by using the mathematical formulas built into the PostScript 
printer language. (wow !) This of course, excludes any scans you placed in your document. (The regular scan rules apply. )

If you want high-quality art or logos or posters with special effects such as gradient screens, distorted objects, etc., you should use one of these programs. (QuarkXpress will do some of these things) Art can also be exported out in EPS format, and used in a page layout program (Pagemaker, QuarkXpress). You must posses a PostScript language printer to fully utilize these programs. Include
all fonts manually. Your print provider does not posses all of your fonts.
Or convert all fonts to outlines, in which case a text problem (typo) cannot be fixed by your print provider.