How to save EPS from Powerpoint.

• File Menu->print
• check "print to file", "color", "current slide"
• click OK
• save as type "all files"
• file name: "fred.eps"
• click SAVE

Now use an editor to edit "fred.eps".

• To first line, add "EPSF-3.0"
• View the file with "gv". Position the cursor at the lower left and upper right corners of the graphics you want to be within the bounding box. Record these coordinates.
• Edit the "%%BoundingBox:" line to replace the coordinates with the correct ones in the format: [lower left corner] [upper right corner]
  
• Save the modified file.

Now you can use the EPS file in, for example, LaTeX documents.