We have both in my office. Our creative, production, and studio departments use Macs. Our administrative, client services, and accounting departments use PCs. It’s about a 50/50 split.
Okay, first, it’s a misconception that Macs just run better or are more reliable, especially with the advent of OS-HeX (Jaguar, Tiger, Panther, whatever), and the new machines with Intel chips are as slow as standing dirt for Photoshop, Illustrator and QuarkXpress unless you have a dual processor.
Macs don’t lock-up or freeze. Pish! Macs are easier to use than PCs. Tosh! The Macintosh has joined the PC in being a headache inducing nightmare, especially on a cross-platform network. Macs don’t get viruses. HAHAHHAHAHAHAH!!! Macs are not subject to spyware attacks. Bzzz! Wrong. It’s been going down-hill for the lauded Macintosh ever since Apple decided to use standard IDE drives and PC RAM.
Unix-Shmoonix - If Unix has made things better for the Mac my network administrator certainly doesn’t see it.
Having said all that, I have a PowerBook at home and prefer it over my PC, not because it’s better, or has fewer glitchety-glitches (as evidenced by twice having to get it repaired—thank goodness for Apple Care), but because of the ‘cool’ factor. It’s also slimmer and lighter-weight than my Dell laptop.
As far as comparability from a user standpoint, I find both PCs and Macs to be virtually the same. Photoshop ‘feels’ a little clunkier to me on a PC than a MAC, but conversely, Word ‘feels’ clunkier to me on a Mac than a PC, so it’s probably just my learned biases. User-created files are now equally usable on both platforms, so no problems there.
By the way Apple/Microsoft, thanks for buying into Internet Explorer for two seconds and then dropping it like a hot potato for (blech) Safari. FireFox forever!
Fonts! Aaaaauugh!!! - I just had to get that out. The fight of TrueType/PostScript fonts, and screen fonts and printer fonts is no fun. Fonts are actually getting better on the Mac, especially since OpenType has been embraced, but there are still compatibility issues with system fonts, library fonts, and installed fonts, especially for Helvetica.
I have to admit there are far fewer boot and connection issues since Apple pretty much did away with the ridiculous hold Extenstions had over the system in OS8 and 9, but application preferences still cause more problems than they should, so much so that trashing preferences is usually the first course of action with dealing with an application that’s decided for no Earthly reason to cease to function properly.
As far as our PCs are concerned, for the most part there are no problems. We get all of our non-Mac computers from Dell. They come in the door, the box is opened, the computer removed, plugged in, ethernet cable is connected, DHCP kicks in and assigns it an IP, and it’s ready for use. No muss, no fuss.
Speed - It’s not true that Macs are faster than PCs, at least not anymore. Comparably configured, they’re about the same. Some apps run slightly faster on a PC, some slightly faster on a Mac, but it averages out.
[QUOTE=Dewey Finn]
Remember that the Macintosh is made and sold as an integrated unit (hardware and software). Windows PCs are manufactured by many companies using an enormous variety of motherboards, video cards, processors, etc, but using a common operating system. Obviously, there are advantages and disadvantages of each approach.
[/QUOTE]
Wrong. Macs USED to be an integrated unit comprised of all like components. No longer.
[QUOTE=tashabot]
My Mac never freezes when running multiple applications (one application might freeze, but the entire computer doesn’t).
[/QUOTE]
Force Quit is your friend. …and I congratulate you for never having experienced a Mac lock-up. 
[QUOTE=tashabot]
The reason Macs don’t get viruses and spyware is, plainly put, because not enough people use Macs to make it worth it for a virus or spyware writer.
[/QUOTE]
No longer true.
To summarize, my PC’s a workhorse, my Mac’s a delicate flower.