Sometimes EMF files will look jagged when they are brought into PowerPoint; but don't worry, as soon as you ungroup them and release them from EMF format, the lines smooth out.
If you are on a Mac, though, this will not help out. EMF files do not import well into Macintosh. EMF is a native file format for Windows that is created by a collection of commands made to the Graphic Device Interface (GDI) file, which is the file Windows uses to draw on-screen objects, as well as print them to non-PostScript printers. Unfortunately there is not a fix for this. If you are on a Mac, use the PowerPoint download.