I have found that the best way for us is:
1) make the Autocad background white
2) resize the Autocad screen until the objects just fit
3) select all the objects
4) go Edit/Copy
5) in Powerpoint, go Edit/Paste Special/Windows Metafile, NOT a link.
This works in Word, etc also. Changing the background to white is not needed for all styles of PasteSpecial, but for some and for some applications it is needed.