1 Round of Ammunition coming up:
(1) The Mac has much better integrated support for image files in the OS, even with Windows 7 Windows handling of images, fonts etc are much much worse than on the Mac (this is due to Windows having an inferior graphics engine)
(2) Aperture 3 doesnt work on the PC (This ones a good one as he cant argue with that, even if you dont use it its good ammunition - especially as the price has come down)
(2a) - neither does iPhoto, and its a heck of a lot better than anything on the PC (He can say what he wants, but everyone on here will point out hes wrong).
(3) The Mac isnt going to crash due to a driver issue and wipe out all your data (Ive had this happen on PCs.. never on a Mac)
(4) CS5 runs a heck of a lot better on the Mac than on the PC
(5) The OS is based on UNIX, so is a lot more stable, powerful and expandable than Windows
Sorry... I don't want to bash, but I have to correct a few very basic errors in your points.
2) Aperture as well as iPhoto are some of the very ******** programs that are for photography. No photographer who knows what programs there are out there would choose to work with either of those. They are very very consumer minded!
Instead you could have suggested something like the best tether program and photo management program that exists: Phase One's Capture One Pro (lastest edition is 6).
That will hands down walk all over both above mentioned.
1) I don't evne know what you're talking about when you write "integrated support for image files"... if #0 is a photographer, she's likely only to be seriously working with one or several of these formats:
- raw
- tif
- jpg
All three are perfectly supported by windows and have been for... well... as far back as I can remember.
4) As for CS5 running better on a mac? Do you base your assumption on two exact same modifications on the two platforms? Or is this just the old school fanboi crap?
2 years ago... yes, I would have agreed that photoshop was nicer to run on a mac. After Windows 7, I'm not so sure anymore.
I run CS5 on a 2.4 core 2 quad pc and I haven't had a single shutdown yet. And it runs smoothly, even with my inferior 3gb of ram. I would love to see how it would run on 8gigs :O
Add to that... I just finished editing a 9 min video shot on Canon with file parts up to 4 gigs, and premiere cs5 handled those perfectly on said pc.
#0 Now here's the real reasons you should
maybe choose one over the other...
Macs are very stable yes... In my fulltime photography job I work on an old duo iMac (it's crap by now :S). But the thing is that I feel like I can trust it. It never crashes, and I know exactly what time during the day I have to restart it to make it work at normal speed again (yeah... it gets slow after 2:30 pm EVERY day

)
The interface is nice and you wont risk deleting some file or messing up folder structures.
Regarding your work flow... I bet you wouldn't feel a difference in your pace, except for the part that you would have to get used to the new interface.
Now since this is an iMac room I'll go along with you wanting that. But I have to tell ya... even though I work on an iMac every day, I wouldn't for my own serious where I want to know and be able to see exactly what Im doing work on an iMac these days.
Glossy screens are pretty and a definite consumer move from Apple. But when it all comes down to it, glossy screens do not give you an accurate image of what you finished work will look like on print (NO.. it wont, and if you think it does, your eyes haven't been trained to see subtle diffences).
In fact, you could risk ending up making your photos flat in contrast and not rich enough in color.
So if you do end up with an iMac, do yourself the favor of getting another screen with anti-glare. Eizo screens are still very nice... *hint hint*
Viruses? It's just a matter of time till evil geeks will construct severe viruses for macs.
And about viruses on a pc, the only reason people get viruses is because they use their perfectly fine tuned working machine for crap such as torrents, porn and double clicking files they don't know what do.
The simple trick is to... not do those things, and then install Zone Alarm. You will never have problems again. Atleast I haven't had any probs since I stopped downloading torrents, watch porn and stopped clicking files I don't know what are and have Zone Alarm turned on 24/7
Money wise... well, you can get cheap ram for iMac if you dare insert it yourself. So that's not too bad... but what will you do if one day you need a bigger or faster hd? If you want a 2nd disc drive to streamline your dvd burns? Or replace that processor for a new shiny one?
Apple is a very closed univers and they really know how to make money on their customers.
On a pc, you open the chassy, remove the old part, install the new part and you're upgraded.
The problem with a pc is that you wont get everything served on a plate. You have to take an interest in how these machines work, what parts goes with what etc.
With an Apple, you don't have to do much thinking and I understand perfectly why some people prefer that.
In short... I doubt you by now will find that much different about pcs and macs in total. It is all about comfort and like you say, familiarity and wether you want someone to do all the work for you for at the price of paying more money or if you can handle those things yourself.
My own situation:
Pc at home, mac at work.
I like the looks and stabilityt of the mac, but I love how my pc world is so free and customizable.
And even though I just wrote all this, I'm still in doubt wether to get another pc or if I'll upgrade to a 8/12 core mac pro next time. Because honestly, I'm not hearing any real reasons why I shouldn't build a pc.
When push comes to shove, the only thing that matters to me is how fast I can do the job I'm supposed to do.