Lets think:
Video Designers/Photo Editors etc. - Check.
Governments - Check, US Gov just bought a bunch.
Companies - Check.
Education - Check.
Gamers - Not so much.
4/5 looks pretty good to me.
More like 2/5, if I give you government (all 50 states and federal too?). You see the price conscious private sector not rolling out OSX powered machines for their rank and file, unlike the "government." Man, that'd be a cool movie. Imagine Hunt for Red October having the sonar being auto-tuned on the G5 and the comms station.
Education:
I'll give you this one, but mostly for the 'intellectuals.'
By that I mean you only have to go online and type.(and is that really a computer anymore?)
So yeah, if you're teaching with wikipedia. Should you actually want to use the software that links the graphic calculators for chemistry, physics, and mathematics uses, no.
Companies? - Maybe.
Company IT Team? - Not so much
Company using the average of 20 different software programs per workstation, +/- 5 depending on department within company: Never.
Retail and Consumer services: No (Especially not for PoS, but Apple store does this, so I know it's possible...)