Your best option for this is to use .eps files. They look great and AutoCAD is capable of producing them (a little known fact that may impress any "AutoCAD/Graphic" or "graphic artist" friends you have. They also scale very well should you wish to adjust their size in the presentation.
How you do it:
Under the FILE pulldown in AutoCAD should be Plotter Manager. You can also get to it by typing _plottermanager at the command line.
Next use the Add-A-Plotter Wizard.
Set it up for "My Computer" when it asks you to Config a New Plotter.
Choose Adobe - Postscript Level 1 for your option (this creates EPS files).
Click next until it asks you where you want to plot it to (perhaps it will ask which port to plot it to). Select Plot to File.
Name it whatever you want (likely something with EPS in the title) and click next until you are out of this feature.
Then just plot normally and choose this new "EPS" printer as your printer. It will even ask you where you want to save your image when it processes the plot.
Finally insert this into your PowerPoint (this might be the only program you have that can read this EPS file, but PowerPoint will love it! It might not "preview" when you go to insert it, but this would be a Windows issue, not a PowerPoint one. Trust me, it will show up just fine when you place it in the document).
It has an advantage over DWF's (yes, you were correct, a DWF is the Autodesk version of a PDF) and PDF's in the fact that more software programs on the graphics end can use them and they will re-scale perfectly inside powerpoint. They also look a lot better than JPG's and scale MUCH better than them. DWG's simply wouldn't work well for your application if we're discussing a PowerPoint slide.
If someone else is producing these images for you, convince them to do the above steps. It adds an extra level of functionality to AutoCAD most people don't realize it has as it's not listed in any of the literature.
I used to do this professionally 2 years ago for a publisher and have hundreds of images posted in dozens of publications (and thousands of copies) world-wide.