I don't know if those ads are the best for the Mac platform but I think that Apple could do something like this:
An ad which shows fast the installation procedure of Mac OS X:
1. Boot from CD
2. Select Country, etc.
3. Fill personal info
4. Start using your Mac
At the end of this ad they could write: Just in 15 minutes you have your Mac ready to work...
Another could be on how you install an update or an app:
1. Log in
2. Double click or even drag & drop
3. Click two or three times (maybe not needed if you drag & drop
4. Start using your updated app or the new one
At the end of this ad they could write: You can update your system in just a few mouse clicks...
Or how to remove an app:
1. Log in
2. Select the app you want to remove
3. Drag & drop at the thrash
At the end of this ad they could write: Clean you Mac faster than you can clean your house
Or how one can burn a CD Mp3 or Audio or Data:
1. Log in
2. Select files
3. Insert empty CD
4. Drag & drop files on it
5. Burn
At the end of this ad they could write: Burn a CD faster than you can write the track titles on its cover...
The same can be done for DVDs. Anyway, I think that people and most important IT people must see how really easy is to use, support and update a Mac. After all aren't companies (their IT depts.) that want more free time to surf online? With Macs on their employers' desktops they can do that and with less money spending too!
Seriously though, I think that the short videos of how the Mac OS X works that anyone can watch at apple.com can, convince someone that his Windows stuff might not be the end all be all, that they knew all this time...