On some shows, the good guys use Macs and the bad guys use PCs.
On Buffy and Angel, the good guys end up using iBooks/iMacs and the bad guys use PowerMacs
On Buffy, Willow had about every generation PowerBook from a 3400 (or similar) to a Lombard/Pismo WITH the rare blue-and white LCD Studio Display (and maybe a blue-and-white tower too). At school she used generic PCs.... but they always ran Mac OS

Angel is glad they still used floppy drives...
Willow ended up with an Airport-equipped 14" iBook that they all shared, and Buffy and her boss both had 20" iMac G4s. At home, her boss had a PowerMac of some kind.
The Evil Trio used PowerMac G4s and heaps of huge Cinema Displays.
And on Angel, I've seen G4 Cubes and Cinema Displays at W&H.
On the software side, both classic Mac OS and OS X were used, and the browser of choice seemed to be IE5.
Most importantly, iTunes played a pivotal role in the final season of Buffy
And of course, the Buffybot was Mac-compatible. Its creator used Macs, and an iBook was used to control it.
Sadly, Macs on Buffy tend to meet bad ends. Hope they had backups.
Now you know....